Not Just Damaged Goods: Higher-Order Capacities and the Argument from Marginal Cases

Chapter
Part of the Philosophy and Medicine book series (PHME, volume 108)

Abstract

If the arguments of Chapter 2 and Chapter 3 are sound, then even the most “marginal” human organisms still have the typical human capacities that are sufficient to generate serious moral status. But this makes my position vulnerable to a version of the “Argument From Marginal Cases” (AMC).

If the arguments of Chapter 2 and Chapter 32 are sound, then even the most “marginal” human organisms still have the typical human capacities that are sufficient to generate serious moral status. But this makes my position vulnerable to a version of the “Argument From Marginal Cases” (AMC).

1 The Dreaded Argument from Marginal Cases

The general strategy of the “Argument from Marginal Cases,”1 as its name suggests, is to argue from the moral status of certain “marginal cases” of human beings to the moral status of certain non-human animals. The term “marginal” here just means “nonparadigmatic”: marginal cases are nonparadigmatic human beings who seem to have (mental) capacities equivalent to the (mental) capacities of non-human animals. The AMC argues that, since this seeming equivalence of (mental) capacities is real, and since any plausible criterion of moral status must be spelled out in terms of (mental) capacities, consistency requires us to conclude that the marginal cases and the non-human animals have an equivalent moral status.2

Although this is the general strategy of the AMC, particular versions of it vary. Each version has, at its core, the comparison of certain marginal cases and certain non-human animals. At least four things account for the differences between the versions.

First, the AMC comes in both critical and constructive versions. Tom Regan, who defends the claim that non-human animals possess rights, is an exponent of both versions.3 His formulation of the critical version runs as follows:
  1. 1.

    Given certain criteria of the possession of rights, some marginal humans and not just all animals will be excluded from the class of right-holders.

     
  2. 2.

    However, humans, including those who are marginal, do have rights and so belong in the class of right-holders.

     
  3. 3.

    Therefore, each and every one of the criteria of which (1) is true must be rejected as setting a requirement for the possession of rights.

     
Regan’s formulation of the constructive version of the AMC is this:
  1. 1.

    Humans, including those who are marginal, have rights and therefore belong in the class of right-holders.

     
  2. 2.

    However, given the most reasonable criterion of the possession of rights, one that enables us to include marginal humans in the class of right-holders, this same criterion will require us to include some (but not all) animals in this class.

     
  3. 3.

    Therefore, if we include these marginal humans in the class of right-holders, we must also include some animals in this class.

     

It is worth noting that premise 2 in the critical version and premise 1 in the constructive version are the same.

The second thing that accounts for the differences between the versions of the AMC is the fact that the AMC comes in both weak and strong versions. The weak version attempts to show that if the marginal cases have rights (or some moral status or other; more on this in a moment), then the non-human animals also have rights. The strong version adds to the weak version some justification for the claim that the marginal cases have rights. Both the critical and the constructive versions of the AMC listed above, as formulated, are weak versions, since each simply assumes (premise 2 in the critical version, premise 1 in the constructive version) that the marginal cases have rights.

This difference between the weak and strong versions allows critics of the AMC to turn the argument on its head. Such a critic can admit that the marginal cases and non-human animals have an equivalent moral status, yet deny that either the non-human animals or the marginal cases have rights. For example, if we begin with the weak version of the argument, which says that if the marginal cases have rights, then the non-human animals also have rights, and if we add the claim that the non-human animals do not have rights, it follows that the marginal cases do not have rights either. And some thinkers are willing to accept this. So then, although many use the weak version of the AMC to establish claims like “vegetarianism is morally obligatory,” there is nothing about the logic of the weak version that prevents others from using it to establish claims like “cannibalism is morally permissible.”

There is a third thing that accounts for the differences between the versions of the AMC, which has less to do with the argument’s form and more to do with its content. Although the AMC is often used by animal rights theorists to refute various criteria for the possession of rights, its overall structure can be used even when the language of rights is not. This is because the comparison at the heart of the AMC is a useful heuristic device for testing any moral status concept. For example, a constructive version of the AMC formulated in terms of serious moral status might run as follows:
  1. 1.

    Humans, including those who are marginal, belong in the class of those who have serious moral status.

     
  2. 2.

    However, given the most reasonable criterion of the basis of serious moral status, one that enables us to include marginal humans in the class of those who have serious moral status, this same criterion will require us to include some (but not all) animals in this class.

     
  3. 3.

    Therefore, if we include these marginal humans in the class of those who have serious moral status, we must also include some animals in this class.

     
The fourth thing that accounts for the differences between the versions of the AMC also has to do with its content. Different versions of the AMC can be generated depending on which marginal cases and which non-human animals are being compared. There is obviously great variety among non-human animals, and there are also many different types of marginal cases. A good illustration of this is found in those passages, quoted in Chapter 1 of this book, from the beginning of Jeff McMahan’s book, The Ethics of Killing: Problems at the Margins of Life. McMahan claims that there are “four distinct categories into which we may sort most or all instances of killing for which there may be a reasonable justification,”4 and one of these categories includes “cases in which the metaphysical or moral status of the individual killed is uncertain or controversial.” The way he begins his discussion of this category illustrates the heterogeneity of the class of marginal cases:

Among those beings whose nature arguably entails a moral status inferior to our own are animals, human embryos and fetuses, newborn infants, anencephalic infants, congenitally severely retarded human beings, human beings who have suffered severe brain damage or dementia, and human beings who have become irreversibly comatose.5

Some of the marginal cases seem to have (mental) capacities that are not equivalent to, but lower than, many non-human animals. (Indeed, some of the marginal cases seem to have (mental) capacities that are the equivalent of vegetables.) The content of any particular version of the AMC will be a function of the specific sorts of beings compared.

The AMC is a hot topic in contemporary applied ethics. A recent book-length treatment of this argument goes so far as to say that the AMC is “an argument that has generated perhaps more light and heat than any other argument in moral philosophy over the last 20 years.”6 Although it is possible to debate the moral status of marginal cases outside of the context of the AMC, the AMC is often lurking in the background of contemporary debates about marginal cases.

My position appears to be vulnerable to a version of the AMC. This vulnerability can be expressed in the form of a dilemma. On the one hand, my position seems to be committed to the idea that many non-human organisms that we know of have a set of typical human capacities, and hence have serious moral status. To see why, focus again on just a single typical human capacity: the capacity to think. Just as the technology of the future might enable us to produce changes in body of a mentally deficient human organism so as to allow her to think like a normal adult human organism, so too the technology of the future might enable us to produce changes in the body of a non-human organism (e.g. a chimpanzee) so as to allow the non-human organism to think like a normal adult human organism. So, if the mentally deficient human organism has a passive higher-order capacity to think right now, on account of what technology might be able to do in the future, the exact same thing can be said about the non-human organism. Of course, the same sort of thing can be said for any typical human capacity. And having the set of typical human capacities is sufficient to generate serious moral status, whether or not the thing having this set is a member of the human species.

On the other hand (and this is the second horn of the dilemma), if my position rejects the idea that many non-human animals that we know of have a set of typical human capacities, and hence have serious moral status, then my position is guilty of some morally objectionable form of “anthropocentrism” or “speciesism”. This is because my position attempts to draw an arbitrary metaphysical or moral line between the humans and non-humans, or between our species and other species. Such line-drawing presumably commits one to the same sort of metaphysical and moral arbitrariness that other morally objectionable line-drawing commits one to—such as sexism and racism.

If my position is indeed forced into this dilemma, this would re-emphasize the resilience of the AMC, since the possession of a certain set of typical human capacities turns out to be just the sort of criteria that plugs in nicely to Tom Regan’s constructive argument mentioned above. Although an appeal to higher-order capacities does have the benefit of allowing us to say what many want to say about marginal cases, it does this only at the cost of admitting that the non-human animals that we are aware of have serious moral status.

However, I will now argue that my position is not forced into this dilemma. Marginal cases of human organisms can be seen to have serious moral status, without being forced into admitting that the non-human animals we are aware of have serious moral status. And this result can be achieved even without resorting to “speciesist” or “anthropocentric” maneuvering.

2 Tooley’s Cat, Boonin’s Spider, McMahan’s Dog, and Balaam’s Ass

Before explaining why my position is not committed to the first horn of the dilemma, it is important to begin by examining the writings of three philosophers who have, in their own ways, formulated arguments which best express the thrust of this first horn: Michael Tooley,7 David Boonin,8 and Jeff McMahan.9

First, Michael Tooley constructs a thought experiment in which a kitten gets an injection that makes the kitten capable of developing thought patterns just like normal adult human thought patterns. Although this thought experiment is part of a longer complex argument against the moral relevance of potentiality, it is the thought experiment itself (and not the longer complex argument) that is relevant to the first horn of the dilemma:

Suppose that at some time in the future a chemical is discovered that, when injected into the brain of a kitten, causes it to develop into a cat possessing a brain of the sort possessed by normal adult human beings. Such cats will be able to think, to use language, to make decisions, to envisage a future for themselves, and so on—since they will have all of the psychological capacities possessed by adult humans.10

The relationship between Tooley’s thought experiment and the first horn of the dilemma is this. My solution to the problem of marginal cases claims that if a future technology could transform an organism so that the organism possesses the immediate capacity to think, it follows that the organism had the higher-order capacity to think to begin with. Tooley’s thought experiment simply fills in the details by making the technology an injection and the organism a kitten. Thus my solution to the problem of marginal cases would seem to imply that, in Tooley’s thought experiment, the kitten had the higher-order capacity to think to begin with. (And since having this and other typical human capacities at some level or other generates serious moral status, it follows that the kitten, even before it received its injection, would possess serious moral status.)

A more explicit formulation of the first horn of the dilemma is found in David Boonin’s discussion of what he calls “the species essence argument.” Boonin summarizes a version of this argument taken from Stephen Schwartz:
  1. 1.

    A person is “a being who has the basic inherent capacity for thinking in the broadest sense regardless of how developed or blocked it is.”

     
  2. 2.

    “…it is an essential property of every living member of the species homo sapiens that it has the capacity to function as a person…”

     
  3. 3.

    “the capacity to function as a person confers on one a right to life…”

    Therefore,

     
  4. 4.

    “being a member of homo sapiens does ensure that one has a right to life.”11

     
The relevant part of Boonin’s criticism of this argument is his objection to the second premise:

The claim that every member of homo sapiens has the capacity to function as a person is false. There can, for example, be human fetuses with such severe deformities that they will never develop a brain capable of sustaining thought, or even any brain at all. These are human beings who have not even the capacity for functioning as a person and so are not persons on Schwartz’ definition of the term.12

Boonin then considers, and quickly rejects, a possible reply that is very similar to my solution to the problem of marginal cases:

One could, I suppose, characterize such a fetus as a person whose capacity for thought simply happens to be “blocked” by a contingent fact about its head. But then it is difficult to see why we should not also call the spider crawling up my window a person. If he were able to develop a big enough brain, he too would be able to function as a person, so he is simply a person whose capacity is blocked by the fact that he will never have a large enough brain.13

The relationship between Boonin’s discussion and the first horn of the dilemma is this. My solution to the problem of marginal cases claims that an organism can still possess a higher-order capacity to think even if certain physical conditions prevent (or “block”) that capacity from being realized. Boonin invites us to consider how the only conditions that prevent (or “block”) a spider from having the immediate capacity to think are certain physical conditions. Thus my solution to the problem of marginal cases would seem to imply that a spider has the higher-order capacity to think. (And since having this and other typical human capacities at some level or other generates serious moral status, it follows that the spider would possess serious moral status.)14

Finally, Jeff McMahan constructs a thought experiment in which a dog gets genetic therapy that makes the dog capable of developing thought patterns just like the thought patterns of normal human adults. McMahan uses this thought experiment to make a fairly explicit statement of the first horn of the dilemma. Since McMahan’s thought experiment includes a technological element (like Tooley’s thought experiment) and is explicitly used to make the point of the first horn of the dilemma (like Boonin’s discussion), the remainder of this section will be spent giving McMahan’s thought-experiment a careful exposition and reply.

There are two basic ideas behind McMahan’s thought experiment. (1) If a human being with a genetically determined cerebral deficit can nevertheless count as having the “intrinsic” potential to develop the cognitive characteristics of a mature human being, in virtue of the fact that the genetic therapy of the future can enable such individuals to overcome these genetically determined cerebral deficits, then a dog can likewise count as having the “intrinsic” potential to develop the cognitive characteristics of a mature human being. (2) If having this “intrinsic” potential is what determines something’s moral status, then there is no difference in the moral status of the dog and the moral status of the impaired human.

To appreciate this thought experiment, it is important to locate it in the flow of McMahan’s longer discussion of “whether the [human] fetus’s potential can plausibly be regarded as a basis for respect” or more generally “as a basis for moral status.”15 McMahan believes that if the fetus’s “potential to become a person” is to be a basis for moral status, then this potential must be grounded in the intrinsic properties of the fetus.16 McMahan then argues that the fetus’s potential to become a person is not grounded in the intrinsic properties of the fetus.

He begins by distinguishing three cases. First, The Normal Fetus is “a developed fetus that is in every way normal and healthy”. Second, The Fetus with a Chemical Deficit is a fetus whose brain is developing normally except that it is deficient in a certain chemical (e.g., a neurotransmitter) without which the fetus will never be a person, because without this chemical, the fetus, even when grown up, will have cognitive capacities that do not surpass the cognitive capacities of a chimpanzee. Third, The Fetus with Cerebral Deficits is a fetus whose brain is developing abnormally in that if it continues on its developmental path, the fetus will never be a person. McMahan then asks a pivotal question: “On what basis might it be claimed that these latter two fetuses are potential persons?”17

McMahan rejects the answer that “these fetuses are both the sort of entity that normally becomes a person,” since

To point out that these two fetuses are entities of a kind whose normal members tend to become persons is not to show that they have the potential to become persons. It is only to note that normal members of the kind have that potential. But these two members of the kind are not normal members. And their abnormality is precisely that they lack something that is necessary for them to become persons.18

McMahan considers a second answer: “In order for X to have the potential to become a Y, it must be possible for X to become a Y.” McMahan is willing to admit that this answer allows for The Fetus with a Chemical Deficit to count as a potential person. After all, he says, we admit that a seed is a potential plant even when it is not given the water it needs to grow into one. But McMahan is not willing to admit that this answer allows The Fetus with Cerebral Deficits to count as a potential person, and he presents two parallel thought experiments to show why.19

His first thought-experiment can be summarized as an argument:
  1. (1)

    A child born without eyes a thousand years ago did not have the potential for sight.

     
  2. (2)

    A child born without eyes in a world in which eye transplants are routinely performed would have the potential for sight.

     
  3. (3)

    But there is no intrinsic difference between these children.

    Therefore,

     
  4. (4)

    The difference between the potentials of these children cannot be a matter of their intrinsic properties.

     
The second thought experiment has the same form as the first:
  1. (1*)

    A fetus with cerebral deficits in a world, such as ours, in which cerebral augmentation is not possible, does not have the potential to become a person.

     
  2. (2*)

    A fetus with cerebral deficits in a world in which cerebral augmentation through genetic therapy is possible would have the potential to become a person.

     
  3. (3*)

    But there is no intrinsic difference between the fetus with cerebral deficits in our world and the fetus in the world in which cerebral augmentation is possible.

    Therefore,

     
  4. (4*)

    The difference between the potentials of these fetuses cannot be a matter of their intrinsic properties.

     
McMahan characterizes the genetic therapy, in premise (2*), as:

A form of genetic therapy that, if administered to the fetus with cerebral deficits, would cause it [to] grow the cerebral tissues necessary for normal cognition, and…the growth of these tissues would be identity-preserving.20

McMahan thinks the upshot of these thought experiments is this. If The Fetus with Cerebral Deficits has the potential to become a person, then this potential is not grounded in the fetus’s intrinsic properties. Therefore, in the case of The Fetus with Cerebral Deficits, the fetus’s potential to become a person cannot be a basis for the fetus’ moral status.

Before going on to explain the rest of McMahan’s argument, it is important to pause and notice something. If the analysis of higher-order capacities presented above is correct, then each of these thought experiments begins with a faulty first premise. Surely, the child without eyes does have the potential for sight even in worlds where this potential never gets realized. A similar remark applies to the fetus with the cerebral deficit. Thus, in the second thought-experiment, McMahan should have argued as follows:
  1. (2*)

    A fetus with cerebral deficits in a world in which cerebral augmentation through genetic therapy is possible would have the potential to become a person.

     
  2. (3*)

    But there is no intrinsic difference between the fetus with cerebral deficits in our world and the fetus in the world in which cerebral augmentation is possible.

    Therefore,

     
  3. ∼(1*)

    A fetus with cerebral deficits in a world, such as ours, in which cerebral augmentation is not possible, does have the potential to become a person.

     

This objection against McMahan’s argument relies upon the idea that an entity’s potentials depend only upon its intrinsic properties plus the laws of nature, and upon the idea that the worlds in (2*) and (3*) are not just any two possible worlds, but are alternative histories of (or alternative times in) the actual world. McMahan’s original argument, on the other hand, seems to assume that an entity’s potentials depend upon what is technologically possible at a given time in a given world.

But McMahan has an answer to this type of objection. For his very next move evaluates what he calls a “more radical” view of potential that would block his argument from succeeding. He characterizes this “more radical” view as follows:

As long as it is physically possible for the fetus with cerebral deficits to develop the cognitive capacities that are constitutive of personhood in a way that is identity-preserving, that fetus counts as a potential person…what the potential essentially consists in is an intrinsic receptivity to an identity-preserving transformation into a person. This is a fact about the fetus itself: that it is the sort of thing that can in principle be transformed into a person while continuing to exist.21

The thought experiment involving the dog now enters the argument as an objection to this “more radical” view of potential:

If it is physically possible, through some as-yet-undiscovered form of genetic therapy, to augment a defective fetus’s brain in a way that will enhance its future cognitive capacities, it is surely physically possible to achieve the same result in an animal—for example, a dog. If, therefore, we claim that a fetus with cerebral deficits is a potential person on the ground that it is physically possible for its brain to develop in ways that would be identity-preserving and would overcome or repair the deficits, we must concede that a dog is a potential person for the same reason. And if we claim that the fetus’s potential to become a person is a basis for moral status (because it is grounded in a suitably intrinsic receptivity to transformation), we must concede that a dog has an equivalent status, other things being equal. Since, however, no one would (or should) accept that dogs are potential persons with a moral status appropriate to their nature as such, we must abandon the broad conception of potential that implies that they are.22

McMahan’s line of reasoning can be reconstructed as a reductio:
  1. (1)

    X is a potential person at time t if and only if it is physically possible for X at time t to undergo an identity-preserving transformation into a person [Definition of “potential person”]

     
  2. (2)

    It is physically possible for a living thing that is a dog at time t, but not a person at time t, to undergo an identity-preserving transformation into a living thing that is a person at a later time t*. [Assumption]

    Therefore,

     
  3. (3)

    A living thing that is a dog at time t, but not a person at time t, is a potential person at time t. [From (1) and (2)]

     
  4. (4)

    If X is a potential person at time t, then X has moral status at time t. [Assumption]

    Therefore,

     
  5. (5)

    A living thing that is a dog at time t, but not a person at time t, has moral status at time t. [From (3) and (4)]

     
  6. (6)

    But a living thing that is a dog at time t, but not a person at time t, does not have moral status at time t. [Assumption]

    Therefore,

     
  7. (7)

    Statement (4) is false. [From (1), (2), (5), and (6)]

     
McMahan concludes that, no matter how the genetic therapy is described, there is always going to be the non-human animal as a counterexample:

There is, I believe, no basis for claiming that the fetus with cerebral deficits has the potential to become a person that does not also imply that a dog has that potential … we should abandon the ambition to include fetuses with cerebral deficits within the category of potential persons.23

The relationship between McMahan’s discussion and the first horn of the dilemma is this. McMahan’s reductio can be easily recast using the concepts of higher-order capacities and serious moral status:
  1. (1a)

    X has a higher-order capacity to think if and only if it is physically possible for X at time t to undergo an identity-preserving transformation into an entity with the immediate capacity to think [Definition of “higher-order capacity to think”]

     
  2. (2a)

    It is physically possible for a living thing that is a dog at time t, but not an entity with the immediate capacity to think at time t, to undergo an identity-preserving transformation into a living thing that is an entity with the immediate capacity to think at a later time t* [Assumption]

    Therefore,

     
  3. (3a)

    A living thing that is a dog at time t, but not an entity with the immediate capacity to think at time t, is an entity with a higher-order capacity to think at time t. [From (1a) and (2a)]

     
  4. (4a)

    If X is an entity with a higher-order capacity to think at time t, then X has serious moral status at time t. [Assumption]

    Therefore,

     
  5. (5a)

    A living thing that is a dog at time t, but not an entity with the immediate capacity to think at time t, has serious moral status at time t. [From (3a) and (4a)]

     
  6. (6a)

    But a living thing that is a dog at time t, but not an entity with the immediate capacity to think at time t, does not have moral status at time t. [Assumption]

    Therefore,

     
  7. (7a)

    Statement (4a) is false. [From (1a), (2a), (5a), and (6a)].

     

In summary, then, the first horn of the dilemma—represented by the arguments of Tooley, Boonin, and McMahan—claims that if certain marginal humans are allowed to count as possessing the higher-order capacity to think, in virtue of what the technology of the future can enable them to do, then certain non-human animals we are aware of must also be allowed to possess the higher-order capacity to think.

The first horn of the dilemma relies upon the assumption that it is possible to perform these transformations on a non-human animal: more precisely, the assumption is that the non-human organisms we are aware of could be given the immediate capacity to think like a normal human adult while still continuing to exist. This assumption is present in the three authors just examined. For example, Tooley’s claim that the injection “causes it [the kitten] to develop into a cat possessing a brain of the sort possessed by normal adult human beings”24 relies upon the assumption that the living thing that is a kitten before the injection is the same living thing as the living thing after the injection. Likewise, Boonin’s claim that “If he [the spider crawling up my window] were able to develop a big enough brain, he too would be able to function as a person…”25 relies upon the assumption that the living thing that is a spider before the increase in brain size is the same living thing as the living thing after the increase in brain size. Finally, McMahan assumes that the living thing that is the dog before the genetic therapy is the same living thing as the living thing after the genetic therapy: “If, therefore, we claim that a fetus with cerebral deficits is a potential person on the ground that it is physically possible for its brain to develop in ways that would be identity-preserving and would overcome or repair the deficits, we must concede that a dog is a potential person for the same reason.”26

My strategy for replying to the first horn of the dilemma is to deny this assumption. I claim that it is not possible to perform these kinds of transformations on a non-human animal: more precisely, it is simply not true that the non-human animals we are aware of could be given the immediate capacity to think like a normal human adult while still continuing to exist.

This envisaged strategy could be fleshed out in one of two ways. First, it could be making a claim about the limits of technology. It may well be the case that, as a matter of fact, the technology of the future will never be able to (for example) take a dog, produce certain genetic changes in it, and end up with an organism that thinks just like a normal human. This is because the sorts of changes envisioned would be physically impossible, due to the way the bodies of organisms work. If the cells in a dog brain reject or attack the human tissues that are injected into that dog brain, the dog will not be able to develop the immediate capacity to think like a human thinks. I am inclined to think that this first way of fleshing out the strategy is more promising than McMahan is willing to allow. But I really do not know enough about the biology involved in such tissue transplants to say for sure. So I will not pursue this first way of fleshing out the envisaged strategy further.

The second way of fleshing out this strategy is to claim that, even if the tissue injected into the dog was not rejected, still, as a matter of metaphysics, the genetic changes done to the dog would not transform the dog in an identity-preserving way. I would like to explore in a bit more detail the two basic ideas that would need to be accepted to sustain this way of fleshing out this strategy:
  1. (1)

    All organisms are members of natural kinds, which means, among other things, that certain sorts of changes to a given organism will be identity-preserving changes and other sorts of changes to that organism will be identity-undercutting changes.

     
  2. (2)

    The changes required to give the ability to think to any of the non-human animals that we are aware of would be identity-undercutting changes.

     

Although these ideas are related, they are also importantly distinct. One could accept the first but not the second, and vice-versa.

There are different ways of defending (1). One way is to rely on the claim that biological species are natural kinds. Since all organisms are members of biological species, it would directly follow that all organisms are members of natural kinds. Unfortunately, this way of defending (1) runs into what is sometimes called the “species problem.” The proper analysis of the concept of a species is a long-standing debate among biologists and philosophers of biology, and this debate shows no signs of being solved in the foreseeable future. There are at least a dozen different rival accounts of what it means for x to be a member of the same species as y.27 While some accounts emphasize the phenotypic similarities between x and y, others emphasize their genotypic similarities, or reproductive potential, or geographical proximity, or propinquity of descent, or some other common feature and/or relationship. Because of this intractable disagreement, defending (1) using the concept of a species would require being very clear about which concept of a species is in view. It would also require justifying this particular concept of a species rather than the other concepts on offer.

Fortunately, there is an easier way of defending (1) that avoids the concept of a species entirely. This is to rely on the claim that there is some unique way of constructing a biological taxonomy such that the most basic categories of this taxonomy are natural kinds. Since all organisms fall into the categories of this biological taxonomy, it would directly follow that all organisms are members of natural kinds.

Many philosophers think that the members of a natural kind possess something intrinsic in common with each other. Elliot Sober, for example, after stating that “a standard philosophical view about natural kinds” is essentialism, which “holds that each natural kind can be defined in terms of properties that are possessed by all and only the members of that kind,”28 goes on to explain that an essentialist definition of gold “must cite a property that is intrinsic to gold things; the cited property [in this case, atomic number 79] does not require that any relations obtain among gold things.” Likewise, T. E. Wilkerson claims that one of the conditions that must be met by any interesting account of natural kinds is that “members of natural kinds have real essences, intrinsic properties that make them members of the relevant kind, and without which they could not be members of the relevant kind.”29

If humans and non-human animals are members of different natural kinds, then it follows that humans do share something special in common with each other that they do not share with non-human animals: namely, a real essence. McMahan’s argument is looking for an intrinsic difference between dogs and humans; the idea that humans and dogs are natural kinds presents an intrinsic property that a human being possesses and a dog does not. Human beings share a real essence; dogs share a real essence; these real essences are different from each other, but each real essence is intrinsic to the respective organisms that possess it.

However, in order for a doctrine of natural kinds to adequately answer the first horn of the dilemma, it needs to be careful not to identify an organism’s real essence with its genome. For consider again the fetus with cerebral deficits. If her set of potentials or dispositional properties is identified with her real essence, and if her real essence is identified with her genome, then it follows that she is not a potential person. After all, her genetic material was the problem to begin with, since it seemed to undercut the idea that she is a potential person.

The contemporary approach to natural kinds, as represented by Kripke and Putnam, usually attempts to identify a thing’s real essence with some structural feature of that thing. For example, if something looks like gold but does not have atomic number 79, then it is not gold; likewise, if something is functionally just like water but does not consist of H2O, then it is not water. When this understanding of natural kinds is introduced to do work in constructing a biological taxonomy, it will end up emphasizing a genetic real essence. For example, if something looks like a duck, walks like a duck, and quacks like a duck, this still does not guarantee it is a duck. It needs to possess the genetic real essence (whatever precisely it is) that all real ducks have. Likewise, if “human” is a natural kind like “gold” or “water”, then unless something possesses the genetic real essence (whatever precisely it is) that all real humans have, that thing will not be a human.

This is a problem that even an advocate of biological natural kinds must confront. For example, T. E. Wilkerson argues that natural kinds exist in biology, but that species are not natural kinds. Wilkerson considers an objection to a Kripke-Putnam approach, namely, the objection that “species are not uniquely determined by genetic constitution” or, in other words, “genetic real essences of natural kinds do not exist.”30 This objection to a Kripke-Putnam approach can point to various examples in real-life biology: there may be a good deal of genetic variation between the parts of the same individual (in plants) or between the members of the same biological kind; conversely, there may be a good deal of genetic similarity between closely related species.31

One reply to this objection might be to claim that: “the genetic feature we are looking for is a structural feature of the genetic material—for example, the number of chromosomes peculiar to each species.”32 But Wilkerson rejects this reply, since not all humans have 23 pairs of chromosomes (for example, those with Down’s syndrome have an extra chromosome) and many plants have multiple sets of chromosomes (a feature called polyploidy). Wilkerson’s conclusion is that “the more we attempt to isolate the genetic features that determine biological species, the more hopeless the task becomes.”33 The problem, as he restates it, is this:

If natural kinds are determined by real essences, and if species are good examples of natural kinds, then we appear to have produced a contradiction, since species are not determined by real essences.34

An obvious solution to this problem is to claim that species are determined by real essences, but that these real essences are not genetic. Wilkerson’s own solution, however, is to keep the real essences genetic and to simply increase the number of natural kinds in biology. Here is how he summarizes it:

There are natural kinds. Each natural kind is determined by a real essence, a property or set of properties necessary and sufficient for membership of the kind in question. The real essence in turn grounds the causal powers of individual members of the kind. Biological natural kinds are determined by genetic real essences which are causally responsible for the behaviour of individual members of the kind. But, since there is considerable interspecific genetic similarity and intraspecific genetic variation, there are far more biological natural kinds than species.35

Whatever the merits of Wilkerson’s proposal may be for systems of biological taxonomy, his proposal is not helpful for explaining how a human with a genetic handicap can be a member of the same natural kind as you and I. For if the real essence that grounds membership in biological natural kinds is equated with the genome, then there would be as many natural kinds as there are genetically diverse individuals. But this proliferation of natural kinds is tantamount to giving up on the doctrine of natural kinds in biology. Imagine a “biological periodical table”, if you will, that is designed to parallel the periodic table of the elements. Just as gold has its own box with its own atomic number, so each genetically distinct individual would have its own box with its own (let us say) genetic number. If a population of genetically identical clones existed, then of course many different instances of the genetic real essence would exist. But everyone else would be all by himself or herself in the biological periodic table. Consequently, if one wants to explain why the human organism with a cerebral deficit and the dog are members of different natural kinds, Wilkerson’s proposal works just fine. But if one wants to explain why the human organism with a cerebral deficit and the normal human organism are members of the same natural kind, the real essence they share must go deeper than, and be different from, a purely genetic constitution. Otherwise, the human with a genetically determined cerebral deficit will be a member of a different natural kind from the rest of us.

There are at least three reasons for believing that an organism’s real essence is deeper than, and different from, its genetic constitution. First, the possibility of an organism surviving a small genetic mutation suggests that an organism’s genetic code should not be equated with its real essence. Second, the fact that it is possible to have more than one genome within the same organism also suggests that an organism’s genetic code should not be equated with that organism’s real essence. Third, the following thought experiment gives us a reason for not identifying an essence with a genotype. Suppose you have a one-celled organism. On Monday, you put it into a state of suspended animation and extract its DNA. For the next 3 days, you tinker with its DNA in a separate part of the lab. On Friday, you reinsert the DNA back into the organism and thaw out the organism. The organism exists even when its DNA has been removed. In other words, the organism continues to have its essence even when its genotype has been removed. Therefore its essence is not its genotype.

One might object to the plausibility of describing this case the way I have described it on the following grounds: “it seems like the one-celled organism is killed, and then a new one-celled organism, with the same DNA as the first organism, is brought into being—a process somewhat like cloning. More generally, genotype seems necessary for something to be an organism at all (even if genotype is not sufficient for something to be an organism). The entity with no DNA (in this example) has no self-actualizing capacities at all.”36

My response to this objection moves in two steps. First, I believe that the pretheoretical language we would use in describing this case is suggestive of the interpretation I have already given. For example, we would say that the organism gets “its” (the organism’s) DNA removed and then returned to “it” (the organism). Second, I believe this first point is at its strongest whenever the extraction-alteration-reinsertion of the DNA is made with an eye towards benefitting the organism. If the DNA were extracted from a one-celled elephant in order to be tinkered with for the sake of that very elephant (for example, say the scientists are genetically modifying the genes that code for the functionality of Dumbo’s elephant trunk, so that when Dumbo grows up he can use his trunk like all the other normal elephants), I believe we would be strongly and rightly tempted to see this as a therapeutic intervention, which begins with Dumbo, ends with Dumbo, and has Dumbo in the middle. The same thing would apply, I believe, if the genetic “therapy” was being attempted on a one-celled human embryo.37

The essence of an organism is partly characterized, but not fully exhausted, by making reference to phenotypes and genotypes. The essence is phenotypic in the sense that the essence is characterized by the range of phenotypes an organism can exhibit while still remaining the same organism. But the essence is not strictly phenotypic, because the characterization referencing the phenotypes is subjunctive: the important thing is not what phenotypes the organism actually has, at this very moment, but rather what phenotypes it would have if it were put in this or that set of circumstances. Consequently, an organism can still have its essence before any of its possible phenotypes have been expressed, and the capacity to realize a given phenotype is more central to its essence than the actual expression of that phenotype. The essence is genotypic in the sense that a genetic structure of an organism is often part of the physical basis for an active higher-order capacity. But the essence is not strictly genotypic, because it is not to be identified with the genetic structure of an organism.

Idea (2), the second basic idea behind this strategy, was that the changes required to give the ability to think to any of the non-human animals that we are aware of would be identity-undercutting changes. To grasp what this means, consider first the concepts of incapacities and essential incapacities. An incapacity is simply an inability to do something: for example, I have an incapacity for speaking Chinese, an incapacity for remembering your experiences, and an incapacity for omnipresence, omniscience, and omnipotence. An essential incapacity is an essential inability to do something, an inability that one cannot lose while remaining who one is: for example, I have an essential incapacity for remembering your experiences, since if I were to lose this incapacity, I would become someone else: namely, you. Likewise, I have an essential incapacity for omnipresence, omniscience, and omnipotence, since if I were to lose this incapacity, I would become someone else: namely, God. However, my incapacity for speaking Chinese is not an essential incapacity, since I can lose it while remaining who I am.

Philosophers have sometimes claimed that a property can be essential to an object in one of two ways. First, a property is kind-essential if its being had by an individual is needed for that individual to belong to a particular kind. Second, a property is individually-essential if the individual that has it could not have existed without having it. Some philosophers have thought that, if a given property is kind-essential to an individual, then that property is also individually-essential to that individual. Others prefer to make room for the thought that a given property might be kind-essential to an individual without being individually-essential to that individual.

Idea (2) should be read as the claim that each of the particular non-human animals we are aware of has an individually-essential incapacity to obtain the immediate capacity to think. As before, however, let me emphasize that I focus on the capacity to think just for the sake of convenience. What matters is that each of the non-human animals we are aware of has an individually-essential incapacity to obtain the whole set of typical human immediate capacities, one of which is thinking.

Another way of grasping the idea behind (2) is to invoke the concept of a modal boundary. There are innumerable ways that an entity can be modified, but an entity’s modal boundary is the metaphysical line beyond which that entity cannot go. For example, the caterpillars we are aware of would cross their modal boundary if they changed into puppies. But the caterpillars we are aware of do not cross their modal boundary merely by changing into butterflies. On the other hand, if we discovered a group of organisms that looked like caterpillars, but that changed into puppies, we would not say that these organisms were caterpillars that had crossed their modal boundaries. We would say that they were not caterpillars at all: perhaps we would call them “scatterpillars”. Even the character from Greek mythology named Proteus had his modal boundaries: even though he could take on the typical capacities of a donkey, and then take on the typical capacities of a human, and so on, still, he could not become omnipresent, omniscient, and omnipotent.

One of the best reasons for believing in basic idea (2) comes from attempting to construct a temporary change argument in which a human temporarily changes into a non-human animal. It seems that there are certain sorts of apparent temporary changes that are not temporary changes at all, but are rather instances of one individual ceasing to exist and another individual coming to exist. Recall the example above where a scientist accidentally steps in front of a machine while it is emitting A-rays. Imagine that the administration of A-rays, instead of transforming this scientist into an individual with a genetic disability, instead transforms the scientist into a dog. I believe that the scientist before the administration of A-rays is not the same organism as the dog after the A-rays. The apparent transformation of the scientist was actually not a case of transformation at all, but one of annihilation and creation: the original scientist was annihilated (or disembodied, for those who believe in the possibility of disembodied existence), and a brand new organism was created. And this is so even if the machine is able to emit B-rays that “transform” the dog into a human organism (who we may call “the resultant scientist”) a few minutes later. The B-rays would not actually transform the dog, but would annihilate (or disembody) it and create the resultant scientist in its place. The resultant scientist would not be the original scientist.

The hypothetical example of “scatterpillars” tells us something important. If we came across a particular non-human animal that appears to have been transformed, in an identity-preserving way, so that it now seems to have the typical human capacities, such as thinking, we have two options for describing this. On the one hand, we could say that this apparently identity-preserving transformation was actually identity-undercutting, and that the original animal ceased to exist (or at least ceased to exist right there, if one wishes to make room for disembodied non-human animal souls) at the moment a new organism began to exist. On the other hand, we could say that this apparently identity-preserving transformation was indeed genuinely identity-preserving, and that we were mistaken in our original thought that this particular non-human animal possessed an individually-essential incapacity to obtain the typical human capacities. The individual that changed was a “scatterpillar” after all, and not a caterpillar.

Denying the numerical identity of the original dog and the resultant organism with the immediate capacity to think is simply the third step in a natural progression, the first two steps of which have already been seen to be acceptable. The first step in this progression (from Chapter 4) dealt with re-arranging an island of raw materials so that it came to constitute a human organism. The mere facts that the original individual (the island) was spatiotemporally continuous with and mereologically indistinguishable from the resultant individual (the human organism) were not sufficient for making the original individual numerically identical to the resultant individual.

The second step in the progression (also from Chapter 4) dealt with changing a part of a human organism so that it came to constitute a new human organism. Here, as in the first step, the original individual was spatiotemporally continuous with and mereologically indistinguishable from the resultant individual. But in addition, the original individual and the resultant individual were both alive and were genetically identical to one another (i.e. they had the same genetic code). Yet these facts were not sufficient for making the original individual numerically identical to the resultant individual.

Whether one is a materialist or a dualist of one stripe or another, one of the lessons learned from these first two steps is this: whatever it is that provides the locus of identity through time for an organism, it is not the elements of spatiotemporal continuity or mereological indiscernability. Nor is it the combination of these elements under conditions where both the original individual and the resultant individual are alive. Therefore, one cannot rely upon these elements when one claims that a dog before the application of technology is the same individual as the resultant individual after the application of technology.

There are at least three objections to this strategy and to the claims that back it up. First, it might be objected that any doctrine of natural kinds in biology is inconsistent with the theory of evolution. In reply, this objection is mistaken for a reason Elliot Sober gives in his evaluation of different evolutionary arguments against the idea that species are natural kinds. Even though the above discussion avoided the species concept, and even though Sober himself does not think species are natural kinds, relying upon him here is instructive because the point he makes is relevant to evolutionary arguments against essentialism in biology. One such argument runs as follows: (1) natural kinds are immutable; (2) species evolve; therefore (3) species are not natural kinds. Sober replies that, just as an atom smasher can transform lead into gold without undermining the idea that the chemical elements have immutable essences, “the fact that a population belonging to one species can give rise to a population belonging to another species does not refute essentialism about species.”38 And just a page later, he says:

In general, essentialism is a doctrine that is compatible with certain sorts of vagueness. The essentialist holds that the essence of gold is its atomic number. Essentialism would not be thrown into doubt if there were stages in the process of transmuting lead into gold in which it is indeterminate whether the sample undergoing the process belongs to one element or to the other. I suspect that no scientific concept is absolutely precise; that is, for every concept, a situation can be described in which the concept’s application is indeterminate. Essentialism can tolerate imprecisions of this sort.39

Sober’s point about the transmutation of elements is relevant to the mutation of organisms. It seems that essentialism about chemical elements does not stand or fall depending on one’s theory about the origin and historical evolution of these elements. For example, if it were to be discovered that all of our present elements originally emerged, very gradually, from a sort of primordial stuff, this would not throw into doubt the theory of natural kinds about gold. But then why should it be any different for biological organisms? It would seem that essentialism about biological organisms does not stand or fall depending on one’s theory about the origin and historical evolution of these organisms. For example, if it were to be discovered that all of our present organisms originally emerged, very gradually, from a sort of primordial soup, this should not throw into doubt the theory of natural kinds about humans.

A second sort of objection is that this strategy is just very difficult to believe, because it does seem possible to imagine a non-human organism being transformed, in an identity-preserving way, in such a way that it comes to think just like a human being. Such transformations pop up all the time in various kinds of literature around the world. Consider the Biblical story of Balaam’s donkey:

Balaam got up in the morning, saddled his donkey and went with the princes of Moab. But God was very angry when he went, and the angel of the Lord stood in the road to oppose him. Balaam was riding on his donkey, and his two servants were with him. When the donkey saw the angel of the lord standing in the road with a drawn sword in his hand, she turned off the road into a field. Balaam beat her to get her back on the road. Then the angel of the Lord stood in a narrow path between two vineyards, with walls on both sides. When the donkey saw the angel of the Lord, she pressed close to the wall, crushing Balaam’s foot against it. So he beat her again. Then the angel of the Lord moved on ahead and stood in a narrow place where there was no room left. When the donkey saw the angel of the lord, she lay down under Balaam, and he was angry and beat her with his staff. Then the Lord opened the donkey’s mouth, and she said to Balaam, “What have I done to you to make you beat me these three times?” Balaam answered the donkey, “You have made a fool out of me! If I had a sword in my hand, I would kill you right now.” The donkey said to Balaam, “Am I not your own donkey, which you have always ridden, to this day? Have I been in the habit of doing this to you?” “No,” he said.”40

Whether or not the event described in this story was historical, it is surely metaphysically possible. And yet this event seems to embody precisely the sort of identity-preserving transformation (of the donkey) that the above view of natural kinds says is not metaphysically possible. The organism before the divine intervention and the organism after the divine intervention are the same organism: “Am I not your own donkey, which you have always ridden to this day?”

One way to reply to this objection is to say that, although the events in these stories are intelligible, the proper interpretation of these events need not admit that the individuals in these stories retained their identity through time. Of course, it may have seemed to Balaam, and his donkey, that the organism after the divine activity was the same individual as the donkey before the divine activity. After all, the resultant organism had at least apparent memories of being beaten, and supposedly it had similar mental states to the mental states of the original donkey. But these sorts of considerations—apparent memories, similar mental states—are notoriously insufficient for genuine identity through time. Perhaps it is preferable to say that Balaam and his donkey were mistaken.

But another way to reply to this objection is to say that, in this particular case, the donkey did not have an individually-essential incapacity to think. Saying this does not commit one to the view that all donkeys have a passive higher-order capacity to think. It only commits one to the view that Balaam’s donkey had a passive higher-order capacity to think. And if it turned out that Balaam’s donkey had a set of higher-order typical human capacities, then, in the case of Balaam’s donkey, we would have to admit that it had serious moral status. When confronted with the case of Balaam’s donkey, we employ the same move that we employ when confronted with a scatterpillar. In both cases, we simply admit that the individual substance was not the sort of thing we had assumed it was at the beginning, and that it did not have the modal boundary that we had originally assumed it had.

A third objection to this strategy agrees with basic idea (1) but denies basic idea (2). There are various alternatives for individuating natural substances. For example, perhaps the relevant substantial kind that a spider is a member of is not spider but rather living animal. On this view, as long as a living animal that is a spider remains a living animal, then that living animal will still continue to exist no matter what sorts of changes it undergoes: the living animal that is a spider could receive a huge brain, and learn philosophy, and indeed could even become a dog or a cat or a human. Or perhaps the relevant substantial kind that a spider is a member of is not living animal, but living organism. On this view, a living organism that is a spider could become an oak tree or an amoeba while still continuing to exist.

The best reply to this objection is that choosing from among these alternatives for the relevant substantial kind—living animal, living organism, and so on—is fundamentally and inevitably a matter of testing our modal intuitions with thought experiments of various kinds. Each alternative has its interesting results, or philosophical bullets to bite, and the task of choosing between them is one of deciding which bullets are the least worst to bite. I believe that the alternative I have suggested is at least as good as, and indeed, better than, the ones suggested by this objection. Does it really seem plausible to claim that the same living organism that is now a spider could one day become an oak tree, an amoeba, a human, and a dog?41

3 How Not to Be a Speciesist

The second horn of the dilemma claims that my position is “anthropocentric” or “speciesist” in some morally objectionable way. But this objection is mistaken, and several of the reasons it is mistaken have already been touched upon in one way or another in the discussion of the first horn of the dilemma. For example, the strategy discussed above deliberately avoided the concept of a biological species when defending basic idea (1). The discussion of real essences and genetic codes was neutral between humans and non-human animals. Likewise, when defending basic idea (2), the idea of a temporary change was revised to take account of the fact that humans, too, can only undergo certain sorts of changes and retain their identity through time. Certain kinds of identity-undercutting changes can happen to living human organisms.

There are at least four more reasons why my position is not anthropocentric or speciesist in any morally objectionable sense. First, my position does not say that the non-human organisms we are aware of do not have serious moral status. My position is a sufficiency account. It is therefore fully compatible with the claim that the non-human animals we are aware of do have serious moral status. It is even compatible with the claim that the serious moral status of non-human organisms is based on their typical capacities. Perhaps the set of typical dog capacities generates serious moral status for anything that possesses it.

Second, my position is willing to admit that, after certain identity-undercutting changes have taken place in a non-human organism, the resulting organism now possesses the set of typical human capacities which generates serious moral status. These resultant organisms have serious moral status, whether or not the original organisms did. For example, if the organism that results from altering Tooley’s kitten (or the organism that results from altering McMahan’s dog, or the organism that results from altering Boonin’s spider) has a set of typical human capacities, then this resulting organism does indeed have serious moral status.

Third, if there are non-human organisms with exactly the same higher-order capacities as humans—for example, if we discovered a race of “shumans” on Mars whose members possess the same set of typical human capacities as you or I, even though they had ZNA instead of DNA in their cells—then these non-human organisms would have serious moral status, even though they were not part of our species. My position is that whatever possesses the set of typical human capacities, whether it is part of our species or not, has serious moral status.

Finally, if some of the non-human animals we are aware of do, in fact, have serious moral status because of the set of capacities they possess, the strategy I used with humans would be quite useful in defending the moral status of the marginal cases of such non-human animals. For just as marginal humans still have the distinctively human set of capacities, so too the marginal chimpanzees still have the distinctively chimpanzee set of capacities. If it turns out that normal adult chimpanzees have serious moral status because of their capacities, then marginal chimpanzees—those suffering from temporary changes, brain damage, mental retardation, and so on—will also have serious moral status. Focusing on the passive higher-order capacities of an organism allows a dog lover to defend the moral status of defective dogs, a cat lover to defend the moral status of defective cats, and a chimpanzee lover to defend the moral status of defective chimpanzees. But it does this without the unwelcome implication that spiders, ticks, and cockroaches have the same moral status as dogs, cats, and chimpanzess.

Footnotes

  1. 1.

    The label comes from Narveson (1977, p. 167).

  2. 2.

    Consequently, the AMC is occasionally called the “Argument for Moral Consistency” because it urges us to be consistent in our evaluation of the moral status of non-human animals and marginal cases. See Dombrowski (1997, p. 24).

  3. 3.

    Regan (1979, pp. 193, 196), quoted in Dombrowski (1997, pp. 27–28).

  4. 4.

    McMahan (2002, pp. vii–viii).

  5. 5.

    McMahan (2002, p. vii).

  6. 6.

    Dombrowski (1997, p. 3).

  7. 7.

    Tooley (1983, p. 192).

  8. 8.

    Boonin (2003, pp. 24–25).

  9. 9.

    McMahan (2002, pp. 302–329).

  10. 10.

    Tooley (1983, p. 191).

  11. 11.

    Boonin (2003, pp. 23–24). There is also an additional part of the argument that says, “since every human fetus is a member of homo sapiens, it follows that every human fetus has a right to life” (p. 24). But this additional part of the argument is not important for focusing on marginal cases.

  12. 12.

    Boonin (2003, p. 24).

  13. 13.

    Boonin (2003, p. 24).

  14. 14.

    Boonin also objects to the second premise because of “human beings who permanently lose their capacity for functioning as a person, such as those whose higher brain regions are irreparably destroyed…” (Boonin, 2003, p. 24). Presumably, any reply to Boonin’s objection along the lines of Chapter 2 would be rejected for the same reasons.

  15. 15.

    McMahan (2002, p. 309).

  16. 16.

    McMahan uses the term “person” as what some logicians call a phase sortal, like the term “adolescent”: an entity can fail to be a person at one time, become a person, and then fail to be a person again. And the grounding he has in mind seems to be epistemic: “there must be something about the fetus now that justifies the claim that it is a potential person” (McMahan, 2002, p. 309, emphasis mine).

  17. 17.

    McMahan (2002, p. 310).

  18. 18.

    McMahan (2002, p. 310).

  19. 19.

    McMahan (2002, p. 311).

  20. 20.

    McMahan (2002, p. 311).

  21. 21.

    McMahan (2002, p. 311).

  22. 22.

    McMahan (2002, p. 312).

  23. 23.

    McMahan (2002, p. 312).

  24. 24.

    Tooley (1983, p. 191).

  25. 25.

    Boonin (2003, p. 24).

  26. 26.

    McMahan (2002, p. 312).

  27. 27.

    For examples, see following anthologies: Ereshevsky (1992) and Wilson (1999).

  28. 28.

    Sober (1993, p. 145).

  29. 29.

    Wilkerson (1988, p. 29).

  30. 30.

    Wilkerson (1993, p. 7).

  31. 31.

    Wilkerson (1993, pp. 7–8).

  32. 32.

    Wilkerson (1993, p. 8).

  33. 33.

    Wilkerson (1993, p. 8).

  34. 34.

    Wilkerson (1993, p. 10).

  35. 35.

    Wilkerson (1993, p. 16).

  36. 36.

    Many thanks to Chris Tollefsen for pressing me on this point.

  37. 37.

    This response leaves open the question of which genetic interventions are genuinely therapeutic, and which are merely frivolous (or harmful) even though they were intended to be therapeutic. If the scientists are genetically modifying the genes that code for the size of Dumbo’s elephant ears, so that when Dumbo grows up he looks just like all the other normal elephants, this may prevent Dumbo from having various positive and negative experiences that he would have precisely because of his oversized ears. Similar things might be said about parallel cases using human embryos.

  38. 38.

    Sober (1993, pp. 146–147).

  39. 39.

    Sober (1993, p. 148).

  40. 40.

    Numbers 22:21-30 NIV (New International Version).

  41. 41.

    One reviewer asked whether my treatment of this topic would still be the same if the envisaged modification to the non-human animal were not a modification involving any changes to the genetic structure of the non-human animal. My answer, perhaps not surprisingly, is yes. If an entity has a given modal boundary, that boundary may not be crossed, period. If an entity has a given essential incapacity, that incapacity cannot be circumvented merely by making non-genetic enhancements rather than genetic enhancements. However, let me take this occasion to propose one other possible way of handling the problem of this chapter that I have not yet developed, much less published, elsewhere. Even if we were to admit that it is possible to take any non-human organism (animal, plant, amoeba, whatever), and change it in identity-preserving ways so that it looks and acts just like a human being does nowadays, and even if we were to thereby admit that this non-human organism possesses, right now, the higher-order capacities (at some very high level) to do the sorts of activities that humans now do (thinking, loving, etc.), this by itself would still not mean that humans have the same sets of higher-order capacities as non-human organisms. For it could be that the set of typical human capacities H of what human are in fact able to do is only a sub-set of a larger set H* of capacities of what humans are in principle able to do. Call H the empirical set of human capacities, and H* the total set of human capacities. Likewise, call D the empirical set of dog capacities, and D* the total set of dog capacities. Even if we admit that D* includes H, this does not mean that D* and H* are the same. But this proposal would require much more development.

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.Department of PhilosophyCalifornia State University, SacramentoSacramentoUSA

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