The argument from agency
The argument from agency suggests that we should reject epiphenomenalism on the grounds that it deprives us of agency in action. The worry is that without being agents with the capacity to act, we wouldn’t have free will, and without free will, we wouldn’t have moral responsibility, thus epiphenomenalism seems to undermine free will and moral responsibility. Of course, this way of putting things assumes that free will requires agency, and that moral responsibility requires free will—I will take these assumptions for granted. My question in this section is: Does epiphenomenalism really deprive us of agency in action? The answer is not that simple, because we don’t have one epiphenomenalism, but many.
Assuming that free will requires the capacity to act, and that this capacity requires some of our mental states to be causes of our actions, it seems to follow that the argument from agency is spot on with respect to Epiphenomenalism (with capital “E”). As previously noted, two views in the literature that allegedly imply Epiphenomenalism are non-reductive physicalism and non-physicalist property dualism, views that I will turn to in Sect. 4.
What about partial epiphenomenalism? This is the view—or better, the family of views—according to which only some kinds of mental states or properties are epiphenomenal. Whether the argument from agency is successful against partial epiphenomenalism depends on what part of mentality we are considering. As previously noted, two notable versions of partial epiphenomenalism are qualia epiphenomenalism and wide content epiphenomenalism. Let’s consider both positions.
If qualia epiphenomenalism is true, then qualia are epiphenomenal properties. Qualia are properties of experiences in virtue of which such experiences are experiences—in virtue of which there is something it’s like to have them. So, qualia epiphenomenalism is explicitly committed to the claim that “the properties in virtue of which we are conscious are not properties in virtue of which events causally contribute to our behaviour” (Robinson 2020: p. 27). On this view, the painfulness of Hilda’s pain experience upon touching a very hot stove doesn’t have any causal role in her saying “ouch!”, or moving her hand away from the hot stove. Does this problematise or undercut Hilda’s capacity to act in anyway? Clearly not, as this is a case of a reflexive behaviour, and not a case of action.
But suppose, just a moment later, upon reflecting on her persisting painful experience, Hilda decides to run cold water on her hand, and then successfully executes this plan. If painfulness is epiphenomenal—as the qualia epiphenomenalist believes—then it doesn’t play any causal role in the successful execution of Hilda’s plan. From this, does it follow that Hilda’s running cold water on her hand is not a free act, or that Hilda is not the agent of this action? I think not, as it is not clear to me that the causal powers of qualia have much to do with having or lacking the capacity to act. It would be odd if Hilda’s pain experience had nothing to do with the fact that she runs cold water on her hand given that she seems to decide to do so upon having a pain experience. In general, it would be very undesirable if we were systematically wrong about the aetiology of our actions. But it is important to note that qualia epiphenomenalism doesn’t say that our experiences don’t have any causal role in our actions. It says that the qualia that are instantiated by our experiences don’t have any causal role. So, even if qualia epiphenomenalism is true, it can still be true that Hilda’s pain experience plays a causal role in her action. On the assumption that qualia epiphenomenalism is true, what is false is the claim that the painfulness of this pain experience is part of the causal story. It may turn out that a view whereby pain experiences are causes but painfulness doesn’t have causal role in this is false. But falsehood is not my question here; the question is whether this view undermines agency. I see no reason to believe that it does.
Am I assuming that an experience can be a cause without the qualia that are constitutive of that experience playing any causal roles? Well, I am assuming that, according to qualia epiphenomenalism, this is can be—and indeed is—the case. But in so doing, I am also assuming that this is a coherent metaphysical picture. I want to stand by this assumption, because I think it is plausible that not all properties of causing events are causally relevant to their effects. Suppose I throw a brick at a window, and the window breaks. As it happens, the brick is red. Surely, the mass and the rigidity of the brick are causally relevant to the breaking; but not all properties of the brick are causally relevant to the breaking. So, some properties of the brick-throwing event (e.g., it being a red-brick-throwing event) are causally irrelevant, although the event itself is surely causally efficacious to the breaking in virtue of its causally relevant properties. The qualia epiphenomenalist—for reasons of her own—thinks that qualia are further examples of causally irrelevant properties of causally efficacious events.
Here, one might object that I am ignoring an important sense in which qualia of our experiences seem relevant to our actions. When Hilda provides reasons for her actions, she sometimes cites the qualitative aspects of her experiences. She says that the painfulness of her experience is why she is running cold water on her hand. Likewise, when she acts in ways such that she is pursuing pleasant experiences, her actions are motivated by the pleasantness of some past experiences that are similar to the ones that she is pursuing. If qualia are epiphenomenal, how can we make sense of these facts? Well, the answer is that if qualia epiphenomenalism is true, these are not facts. What is important is that these not being facts doesn’t undermine the fact that Hilda’s mental states cause her action. If these are not facts, then there is a sense in which our claims to be ideal agents are seriously compromised. But the argument from agency doesn’t rest on the assumption that we are ideal agents. And even if it did, so much the worse for it: we are often wrong about the reasons for our actions, we sometimes fail from the weakness of the will, and these already seem to show that we are not ideal agents. If qualia epiphenomenalism is true, then there is yet one more reason why we are not ideal agents. However, none of this means that we lack the capacity to act and free will.
The more relevant examples of mental states, as far as agency is concerned, are propositional attitudes. Consider the following simplified example. Upon hearing knocking, I believe that someone is at the door, and want to find out who is at the door; the pairing of my belief and desire causes me to open the door. Should it turn out that beliefs and desires can never be causes, scenarios like this may never obtain. We have seen that one example of partial epiphenomenalism holds that intentional mental states with wide content are epiphenomenal. On the assumption that externalism is true, beliefs and desires are standard examples of intentional mental states that have wide content. Then, one might think that this kind of partial epiphenomenalism is undermined by the argument from agency.
But the problem is merely apparent. If wide content epiphenomenalism were to be understood as the view that the beliefs and desires that are the vehicles of wide content are epiphenomenal, on the view that all beliefs and desires have only wide content, wide content epiphenomenalism would undermine our capacity to act as agents. But there is no reason to understand wide content epiphenomenalism as a view about the vehicles of wide content. In fact, if we were to understand vehicles of content in the standard sense, namely as “physical particulars that bear contents and whose causal interactions explain behaviour” (Shea 2018: p. 15, emphasis added), wide content epiphenomenalism, understood as a view about vehicles of wide content, would be self-contradictory.
Suppose that externalism is true for intentional mental states, and my belief that there is water in the bathtub is not a belief that my Twin Earth doppelganger (around whom there is XYZ, not water) shares with me. Instead, my doppelganger believes that there is XYZ in the bathtub. Suppose, upon believing that there is water in the bathtub, I put my toddler in the bath. If it is true that this view implies that wide content is epiphenomenal, it follows from this view that the fact that the content of my belief corresponds to water (and not to XYZ) has no causal role whatsoever in my putting my toddler in the bath. Something that does not follow from this view is that my belief, i.e. the vehicle of the relevant content, has no causal role in my putting the poor creature in the bath. Again, this view may be false, but it is not obvious at all that it implies that my beliefs are not causes of my actions.
As I suggested in Sect. 2, there is reason to formulate wide content externalism as a quausal epiphenomenalist view: my belief that there is water in the bathtub causes me to put my toddler in the bath, but not in virtue of being a belief about water. Let’s consider the quausal versions of epiphenomenalism in relation to the argument from agency.
I believe none of the quausal variants of epiphenomenalism fall prey to the argument from agency; at least, not very easily. There is no reason to treat the four versions of quausal epiphenomenalism separately, as I think the same point applies to all. For us to lack the capacity to act, for us to cease to be agents, what is required is that our mental states fail to cause our actions. If my beliefs and desires are causes of my actions, but not in virtue of being beliefs and desires (or not in virtue of having the relevant wide content), I still have the capacity to act, my mental states still cause my actions, and hence I am the agent of my actions. In other words, mental causation is sufficient for action, mental quausation is optional.
In the forgoing discussion—throughout the last five paragraphs—I have assumed that it is the pairings of beliefs and desires that cause actions, and such causings can be sufficient for agency in action. One might worry that this assumption is too weak—i.e. too easy to satisfy. In particular, if one holds that the relevant mental states that cause action must also provide reasons for actions (see Davidson 1963), then it is not clear that causation by the vehicles of mental content alone can satisfy the requirement for agency. After all, how can a pure vehicle—without reference to a content—provide reason for an action?Footnote 11 Likewise, if one holds, with Mele (1992), that “our desires, beliefs, and the like … help explain behaviour … at least partly in virtue of their content” (ibid.: p. 11, emphasis added), and moreover that such explanation is a requirement for agency in action, then it is probably false that mental causation without mental quausation can ever be sufficient for agency in action. From this, it follows that this particular epiphenomenalist position—i.e. wide content epiphenomenalism understood as a quausal epiphenomenalist view—is in tension with the so-called “standard” causal theory of action which subscribes to these claims.Footnote 12 This is bad news for wide content epiphenomenalism insofar as the argument from agency is presented with the assumption of the causal theory of action in the background. Upon reflection, this shouldn’t come as a surprise: the causal theory of action seems to require exactly what wide content epiphenomenalism and quausal epiphenomenalism more generally explicitly reject: mental quausation by content. Therefore, although the argument from agency can be mounted against wide content epiphenomenalism, wide content epiphenomenalists can resist it by rejecting the standard causal theory of action.
Hence, putting Epiphenomenalism aside, I have argued that epiphenomenalist views or epiphenomenalist implications of some views are largely unaffected by the argument from agency. I shall now turn to the argument from self-knowledge.
The argument from self-knowledge
The main epistemological worry about epiphenomenalism that I shall focus on is about the possibility of self-knowledge, or knowledge of one’s own mind. An important background assumption in presenting this problem is that knowledge requires causal relevance, so what is known has some causal relation to the knowing agent’s knowledge (Goldman 1967: pp. 358–9). The worry is this: if our mental states don’t have any causal relevance, how do we get to know them? The argument from self-knowledge is motivated by the intuitive power of this worry.
Assuming either knowledge is a mental state or a knowing subject’s beliefs that partially constitute her knowledge are mental states, if self-knowledge requires mental causation, it requires same-level causation, not downward causation. Because of this, I will set downward version of epiphenomenalism aside. I will also leave Epiphenomenalism aside (until Sect. 4). That leaves us three versions to consider: partial epiphenomenalism (in particular qualia epiphenomenalism and wide content epiphenomenalism), quausal epiphenomenalism, and partial quausal epiphenomenalism.
Let’s start with qualia epiphenomenalism as an example of partial epiphenomenalism. The worry is that qualia epiphenomenalism implies that the knowledge of qualia is not possible: I can’t know the qualia of my own experiences. Read one way, this is very dramatic. If we equate the “qualia” talk with “what it’s like” talk, it might even sound like this view suggests that I can’t know what it’s like for me to see something red when I see something red. However, as I shall argue, even coupled with the background assumption of a causal theory of knowledge, qualia epiphenomenalism doesn’t imply any of this.
There are two different ways of understanding qualia and how they might relate to our knowledge of them. On the first understanding, qualia are simply properties of our experiences in virtue of which there is something it’s like to have these experiences. This understanding is neutral on whether we are meant to be acquainted in our consciousness with the very properties (or instances thereof) that are responsible for our consciousness. So, on this understanding, knowledge of our own experiences doesn’t require any form of direct acquaintance with the qualia that are constitutive of our experiences. In other words, this understanding of qualia leaves it open as to whether qualia are directly or immediately apprehensible in consciousness. Therefore, even if knowledge of an experience requires a causal relation that one bears to that experience, such knowledge does not require the causal efficacy of qualia that are constitutive of that experience.
On a second understanding, qualia are not only the properties of our experiences in virtue of which there is something it’s like to have these experiences, but they are also the properties that we are directly acquainted with in our experiences. Dennett (1988), in his critique of the very concept of “qualia”, argues that qualia must be properties of this kind. He says: “since they are properties of my experiences … qualia are essentially directly accessible to the consciousness of their experiencer … or qualia are properties of one’s experience with which one is intimately or directly acquainted” (ibid.: p. 385, emphasis added). If qualia, understood this way, don’t have causal powers, how could we be acquainted with them? How could they cause our acquaintance of them? If they can’t cause our acquaintance of them, then we can’t be acquainted with them. This is absurd, and in fact paradoxical, given that we are defining qualia partially as properties that we are directly acquainted with.
I concede that if qualia are to be understood this latter way, and direct acquaintance requires causal connection, then we would have an untenable combination of views. Qualia epiphenomenalism would not be only implausible, but also paradoxical. However, for this very reason, it would be odd for a defender of qualia epiphenomenalism to understand qualia as direct objects of our acquaintance and to also hold a causal theory to explain how we are acquainted with our qualia.
In response to this formulation of the argument from self-knowledge, qualia epiphenomenalists can do either of the following two things. First, they can reject this second way of understanding qualia and simply hold that qualia are properties of our experiences in virtue of which we have conscious experiences, but they are not properties that we are acquainted with. I believe this is a coherent view, because I don’t think Dennett’s inference—quoted above—is a valid one. From the fact that F is a property of my experience E, it doesn’t follow that by having E, I am directly acquainted with F. To be clear, on this view, examples of qualia are not going to be sensory properties, such as phenomenal redness. But this is an acceptable result, as phenomenal redness is not a property of an experience—in the same way that redness is not a property of a picture of a red tomato. (Some things that partially constitute the picture of a red tomato are red, but the picture itself is not red.) On this view, when a subject experiences phenomenal redness R, there is something it’s like for her to experience R, and this is partially because her experience instantiates a quale Q (where Q ≠ R).
Second, qualia epiphenomenalists—should they take qualia as properties that we are directly acquainted with—can reasonably help themselves to a non-causal account knowledge of qualia, or phenomenal knowledge. They can, for example, accept Nagasawa’s (2010) view that such acquaintance is a constitutive relation, rather than a causal one: a subject’s “phenomenal knowledge about qualia q is partly constituted by q” (ibid: 52). On this view, we might want to require a causal connection when explaining our knowledge of objects in our external environment, but we don’t need to do this in order to explain our knowledge of our own experiences. Whatever the merits of this account of phenomenal knowledge might be, it is clear that it is an alternative to the causal account, and it helps qualia epiphenomenalists maintain a non-paradoxical position.
What about wide content epiphenomenalism? If the kind of epiphenomenalism that is supposedly implied by externalism is true, then, with the assumption of the causal theory of knowledge, it follows that we don’t always know the contents of some of our intentional mental states. But consider an alternative option whereby mental states have both wide content and narrow content, where the latter is the kind of content that supervenes on the intrinsic properties of the bearers of the relevant mental state. Following this alternative option, it is possible to argue that when one has a particular belief, one knows only the narrow content of the belief. I am not in the business of defending this alternative option; I simply want to note that wide content epiphenomenalists who want to resist the argument from self-knowledge have a coherent way of doing so.
Finally, let’s consider the two relevant versions of quausal epiphenomenalism together. Applied to quausal versions of epiphenomenalism, the epistemological worry is that if mental states or properties can’t be causally efficacious in virtue of being mental, then we couldn’t know, or be acquainted with, them. If this conditional claim is true, then quausal epiphenomenalism and its variants imply scepticism about our own minds. The obvious route for quausal epiphenomenalists is through denying this conditional claim. Even if a causal theory of knowledge is presupposed, from this presupposition alone it doesn’t follow that what is known must be known in virtue of all of its properties; some properties of the objects of our knowledge may be causally inefficacious. If quausal epiphenomenalism is true, then examples of such causally efficacious properties include properties such as being mental: some (or all) mental states are such that their being mental is not causally efficacious to how they are known.
All in all, full-strength Epiphenomenalism aside, there is no reasonable version of epiphenomenalism that is refuted by the argument from self-knowledge. This, I say, with the assumption that the knowledge of one’s own mental states and properties requires a causal relation. Of course, if one were to drop this assumption, the argument from self-knowledge is unfounded even against full-strength Epiphenomenalism.