Tests for intrinsicness tested

Perfect Duplication, as formulated, is not entirely satisfactory. Take for instance the property of having the same colour as the object at the entrance of the machine. That property, says van Inwagen, gets copied, and so, by this test, is intrinsic. But this, he avers, is quite obviously wrong; it is relational. He therefore holds that this test is “useful, but fallible”, a good rule of thumb—for two reasons. First, failure is conclusive: a property that fails the test has to be relational. Second, the relational properties that pass the test are rather contrived (van Inwagen 2009: 34).

A second test involves the notion of a ‘real change’ as opposed to a ‘mere Cambridge change’. This distinction is due to Geach (1969: 71–2) who introduced it in his discussion of an account of what it takes for an object to undergo change—the account being that an object has changed just in case it has lost (or gained) some property. Geach has argued that this account cannot be correct. For consider, he urges, when Socrates becomes shorter than Theaetetus simply by virtue of the latter’s growth. Then Socrates acquires a new property, viz. the property of being shorter than Theaetetus, and on the account under consideration this means that Socrates changes. But, Geach muses, this change is not a real change in Socrates; it is a real change in Theaetetus. The change in Socrates is a ‘mere Cambridge change’.⁴

These are the tests that we shall be considering. After showing that they are inadequate, we will consider certain possible fixes, and we will argue that no such fixes are plausible.

Let us recall the piece of metal which has [a], the property of being a one-euro coin. We asked whether that piece of metal’s loss of [a] would constitute a real change in it. What our discussion brought out was this: if the piece of metal loses [a] due to melting, then the metal loses [a] because of a real change; after all, the melting of a piece of metal is a real change of it, and hence [a] is intrinsic to the metal. But if the piece of metal loses [a] due to a change of the law, then the piece of metal undergoes a mere Cambridge change which means that [a] comes out as extrinsic.

However, we see nothing special about our examples and suspect that for most properties it will be possible to generate analogous contradictory results, provided that one is imaginative enough. This is a problem because it means that Real Change* will typically yield the result extrinsic in cases where the intuitive result is intrinsic.

To convince ourselves of this, let us consider one more example property, which is intuitively intrinsic. In particular, let’s consider the property we removed from the coin, which generated both a loss of [a] and a real change: the property of being solid. Surely, any way of removing the solidity of the coin will yield a real change in the coin. In that case, Real Change gives a determinate and intuitively satisfying result: solidity is intrinsic.

With a little imagination, however, we can remove the coin’s solidity, but yield the intuition that the coin has not undergone a real change. Let’s first get clear on the concept of solidity. A solid is often defined as a rigid material which does not flow when it is subjected to moderate forces (Doremus 1994: 339). Here ‘moderate’ is the important notion. Take a Maxwell body, such as glass. Glass flows like a fluid for small forces over long timescales (e.g. gravitational effect on window panes), is solid for small forces over short timescales (e.g. knuckle tap), and is brittle for large forces over short timescales (e.g. throwing bottles). Now consider a continental plate, which is solid when we walk on it (small force, small timescale), elastic in response to an Earthquake (large force, medium timescale), brittle in response to an asteroid (large force, small timescale), but fluid on the timescale of the age of Earth.

With this in mind, let’s remove the solidity of the coin without really changing the coin, i.e., by only changing properties of objects that are wholly distinct from the coin. We simply change them in such a way so that what counts as ‘moderate forces’ changes: the dynamics of other objects relative to the coin are slowed right down so that from the perspective of the coin, only small forces are applied to the coin over large time-scales. But from the perspective of all other objects, these forces and time-scales are now considered the norm. For example, after holding the coin in your hand only over what you would (in this hypothetical scenario) consider a moderate time-scale, the coin, in response to gravity (moderate force), will ooze out across your palm into a puddle. No real change in the coin (at least prior to these gravitational effects), only a change that can be compared with Socrates when he becomes shorter than Theaetetus due to the latter’s growth. But we have a loss of solidity, so by Real Change*, solidity is extrinsic. So for any putative intrinsic property of an object, just think of a possible world (however outlandish) in which the property is lost (or gained) simply by changing the states of other objects. In doing so Real Change* will always yield extrinsic.

The mistake made by Real Change (and Real Change*), we diagnose, is that it gets things the wrong way around. It seems that what it is for an object to undergo a real change (if this is meaningful notion at all) is for the object to lose an intrinsic property. And so to test for a real change we need to look for a change in intrinsic properties. But for this we need an independent test for intrinsicness.

What about property [c], wearing a golden ring? Recall that Perfect Duplication failed to yield a result since it left open whether we should remove the ring before duplicating the Queen. This problem is not solved by Perfect Duplication* since this problem concerns what we feed into the machine, not where we locate the machine. And recall that Lonely applied to [c] failed to yield a result for the same reason. Perhaps the solution (for both Perfect Duplication* on [c] and Lonely on [c]) is simply to get clear on the referent of ‘Queen’: what are the objects that compose the Queen? Thus, we first make a judgment about composition, and then we apply the tests.

Naturally, we would not take the ring to be a component part of the Queen, and so we would remove the ring before the duplicator or the lonely world even come into play. If this is a legitimate response then we are finally having some success; for both tests now (apparently) give determinate and intuitively correct results.

Should we conclude that Perfect Duplication* and Lonely are adequate tests for intrinsicality? We think not. The relevant thought experiments now require that we isolate the ultimate component parts of the Queen. For Perfect Duplication*, we must isolate the relevant constituents so that we know what to put into the duplicator. For Lonely, we must isolate the relevant constituents so that we know what objects are to be made lonely. The problem is that unless we first understand the atomic constituents of the Queen, we have no clue as to what properties the Queen will retain if made lonely, or what properties the Queen’s duplicate will retain. The final section is dedicated to pressing this problem.

Our remaining tests, as we will now argue, are infected by a problem analogous to Hempel’s famous dilemma for materialism (Hempel 1969). Materialism (roughly) states that everything is (or is made of, or is grounded in) matter. Materialism’s dilemma is that ‘matter’ is either defined by present physics or by ideal future physics. If the former, materialism is (most likely) false since our present theories of matter are (most likely) false. If the latter then we don’t know what materialism says because we don’t know what ideal future physics says. This dilemma is relevant for Lonely and Perfect Duplication*. For when performing the relevant thought experiments we need to isolate the atomic constituents of the objects we are testing for the presence of intrinsic properties, before sending those objects (or their duplicates) into other possible worlds. The first step—isolating the atomic constituents—will require some understanding of those constituents. We either use our current limited understanding of the atomic constituents, or we use non-existent (ideal completed) physics. Either way, we have no reliable way of executing the tests for a given case, as we will now argue.

The second horn of the dilemma is clearly problematic. Our tests are intended to offer ways of determining whether a given property is intrinsic or not. However, if the tests require a physical theory we do not have (ideal future physics) then we simply cannot perform the tests.

Billiardballism is self-explanatory. Let’s begin by considering how Lonely categorizes the Queen’s shape, and the Queen’s wearing a golden ring, given Billiardballism. We take all the atoms that compose the Queen, and remove every other atom, to see whether the Queen retains her shape and her ring. In the lonely universe the atomic billiard balls retain their configuration. Since the Queen’s shape presumably supervenes on the configuration of her atomic parts, the Queen presumably retains her shape. Her shape is therefore intrinsic.⁸ Since we do not deem the atomic parts of the Queen’s ring to be parts of the Queen, the ring’s parts are removed, so the Queen does not retain the ring. Her wearing a golden ring is therefore extrinsic.

Perfect Duplication*, given Billiardballism, will effectively give the same results: since the configuration of the Queen’s parts are duplicated, her shape is duplicated (necessarily), so her shape is intrinsic; since the ring’s parts are not duplicated, her ring is not duplicated (necessarily), so her wearing the ring is extrinsic.

According to this quantum state, particle 1 is not (strictly speaking) in a superposition of being located at Xa and being located at Xc: it is in a nonseparable superposition with particle 2. This entails that particle 1 has no position of its own: the nonseparable state is (as the name suggests) not decomposable into individual component position states. Global nonseparability is the thesis that no particle has a position of its own: every particle is in a nonseparable superposition with every other particle.

Now consider what happens when we try to make the Queen’s constituents lonely, given Global Nonseparability. Since the positions of 1 and 2 are nonseparable, if we remove particle 2 we inevitably remove particle 1. The idea is that removing particle 2 entails that particle 2 no longer has a position. But removing 2’s position inevitably removes particle 1’s position, thereby removing particle 1 itself. Given global nonseparability, particle 2’s position is nonseparable with all the particles that compose the Queen. So removing particle 2 removes the Queen.¹⁰ Similarly for the Queen’s property of wearing a golden ring: since the positions of the ring’s constituents and the positions of the Queen’s constituents are nonseparable, removing the ring (i.e. literally removing it from the world in the process of making the Queen lonely) removes the Queen. This would appear to destroy the test entirely: given Global Nonseparability, it is simply not possible to make the Queen lonely.

Assuming Global Nonseparabilty, is there any way to recast Lonely in such a way that it can yield determinate results? We’ve been working with a conception of Lonely under which one removes all particles except for those that constitute the property bearer of interest. But we could try to make the property bearer lonely in another way, viz. by transporting it to an empty possible world. But even that wouldn’t help: how could particle 1 be transported to another world by itself, given its nonseparability with particle 2? Perhaps, however, we can fix Lonely with an additional ad hoc stipulation: if particles to be made lonely happen to be nonseparable from particles that are not to be made lonely, then “separate” them first. However, since separating nonseparable particles requires changing their physical states entirely, the question arises: what states do we change them to before making them lonely? The states that guarantee that Lonely yields intuitive results? But this would make Lonely circular. Furthermore, even if we fixed on some way of separating nonseparable particles, we have no reliable way of knowing what effect that will have on a complex object like the Queen, so we would not know what properties she would retain, so Lonely still gives no results.

Finally, one might think that if it really is the case that removing particle 2 removes the Queen, then this is evidence that particle 2 is actually a part of the Queen after all. But then given global nonseparability, the Queen is composed of every particle in the universe. Removing every particle that does not compose the Queen then means removing nothing. Alternatively, transporting the Queen to an empty world means duplicating the actual world. Consequently, every property of the Queen would turn out to be intrinsic. This is the bullet that we think defenders of Lonely must ultimately bite. Before explaining the problem with this consequence, we will show that the same problem arises for Perfect Duplication*.

As with Lonely there are two ways we can understand the duplication test: either the duplication machine puts the duplicate in the actual world (Perfect Duplication) or it puts the duplicate in any possible world (Perfect Duplication*). Either way, the problem is that we cannot literally isolate the Queen’s parts to put them (and only them) in the machine, given their nonseparability with all other particles. Duplicating the Queen in the actual world (in accordance with Perfect Duplication) requires that the Queen-duplicate is constructed so that her parts are nonseparable from every other particle in the universe in the same way as the Queen-original. We cannot see any way of making sense of this situation. Alternatively, if the machine puts the Queen in an alternative possible world, then to be a duplicate her nonseparable state must remain, and so the machine does not duplicate only the Queen, but duplicates the entire actual world in the alternative possible world. Here we at least get meaningful results, but ones which deem all of the Queen’s properties intrinsic. This is the bullet that we think defenders of Perfect Duplication* must ultimately bite.

We now have our illustration of (horn one of) our Hempel-like dilemma: Lonely and Perfect Duplication* give radically different results depending on whether we appeal to a theory resembling classical physics (Billiardballism) or a theory resembling modern physics (Global Nonseparability). For example, on the former theory, only a small portion of the Queen’s properties are intrinsic, while on the latter, all of them are.

Is there any way other to salvage our tests? One common reaction we have faced by defenders of intrinsicness consists in the following suspicion: our argument somehow depends on the assumption that worlds containing lonely individuals (or worlds that host the duplicates) are governed by the same laws of nature as the actual world. The upshot is then meant to be that the interpretation of quantum mechanics is irrelevant to what happens in such worlds.¹¹ However, this reaction is based on a fundamental misunderstanding of the nature of quantum nonseparabilty.

The reaction appears to suppose that by placing the Queen in a world with different laws (or no laws at all), the nonseparabilty of the Queen’s components somehow vanishes. But this is wrong. Imagine that we aim to make the Queen lonely. Will removing the laws of quantum mechanics remove the nonseparabilty of the Queen’s components? No it will not. The reason is that nonseparabilty refers not to features of the laws of quantum mechanics, but to physical states that are brought on by the laws of quantum mechanics. If you remove the laws of nature you do not thereby remove the physical states that those laws previously gave rise to. This reaction therefore appears to treat nonseparability as a feature of physical laws when in reality it is a feature of physical states.

Perhaps what the defender of intrinsicality wants is this: when the Queen is duplicated to a possible world with different (or no) laws, or when she is made lonely (in a way that removes quantum laws) then any physical states that can only be brought on by actual-world-laws must be removed. But this is no help either: how do we go about removing the relevant physical states of the Queen (or her duplicate)? As mentioned above, doing so will inevitably change the Queen. But there is no fact of the matter as to how this will change her! The defender of intrinsicality may want to change the Queen so that she is gauranteed to retain only those properties that are intuitively intrinsic. But then the test itself becomes superfluous, and we are left with no reliable way of testing for intrinsicness.

Are there any other ways out for the defender of intrinsicality? Perhaps one could reject Global Nonseparability in some way. Let’s consider two responses along these lines. The first denies modern quantum mechanics in general, the second denies Global Nonseparability more specifically.

This brings us to the second response: instead of denying quantum mechanics, just deny Global Nonseparabilty, and advocate an alternative understanding of quantum mechanics. There is some precedent for this. After all, quantum mechanics faces difficult problems, which have given rise to a number of so-called “interpretations” of quantum mechanics, which are essentially different physical theories attempting to deal with those problems. And in particular, some interpretations introduce additional fundamental ontology over and above what is described by Global Nonseparability (e.g. Bohm 1952). Perhaps it could be argued that such additions (and their composites) have some intrinsic properties that our tests classify in an intuitively satisfying way. However, this simply brings out how sharp the first horn of the dilemma is: there is no consensus at all as to which (if any) is the correct interpretation of quantum mechanics. Thus, for even the most mundane properties (such as the Queen’s wearing a golden ring), our tests only have a chance of giving intuitive results under very specific, highly controversial, interpretations of quantum mechanics. The fact that intuitive results may only obtain under theories resembling classical physics suggests that intrinsicality may just be a notion that belongs to a metaphysics that builds on a now outdated physics. At any rate, we conclude that the tests for intrinsicness considered here cannot be relied upon.