One-thinker colocationism

Colocationists about human beings think that in my chair are two colocated entities: a human person and a human animal. Both of them are made of the same stuff, both of them exhibit the same physical movements, etc.

The standard argument against colocationism is the two thinkers argument. Higher animals, like chimpanzees and dogs, think. The brain of a human animal is more sophisticated than that of a chimpanzee or a dog, and hence human animals also have what it takes to think. Thus, they think. But human persons obviously think. So there are two thinkers in my chair, which is innately absurd, plus leads to some other difficulties.

If I were a colocationist, I think I would deny that any animals think. Instead, the same kind of duplication that happens in the human case happens for all the higher animals. In my chair there is a human animal and a person, and only the person thinks. In the doghouse, there is a dog and a “derson”. In the savanna, one may have a chimpanzee and a “chimperson”. The derson and the chimperson are not persons (the chimperson comes closer than the derson does), but all three think, while their colocated animals do not. We might even suppose that the person, the derson and chimperson are all members of some further kind, thinker.

Suppose one’s reason for accepting colocationism about humans is intuitions about the psychological components of personal identity: if one’s psychological states were transfered into a different head, one would go with the psychological states, while the animal would stay behind, so one isn’t an animal. Then I think one should say a similar thing about other higher animals. If we think that that an interpersonal relationship should follow the psychological states rather than the body of the person, we should think similarly about a relationship with one’s pet: if one’s pet’s psychological states are transfered into a different body, our concerns should follow. If Rover is having a vivid dream of chasing a ball, and we transfer Rover’s psychological states into the body of another dog, Rover would continue the dream in that other body. I don’t believe this in the human case, and I don’t believe it in the dog case, but if I believed this in the human case, I’d believe it in the dog case.

What are the reasons for the standard colocationist’s holding that the human animal thinks? One may say that because both the animal and the person have the same brain activity, that’s a reason to say that either both or neither thinks. But the brain also has the same brain activity, and so if this is one’s reason for saying that the animal thinks, we now have three thinkers. And, if there are unrestricted fusions, the mereological sum of the person with their clothes also has the same brain activity, thereby generating a fourth thinker. That’s absurd. Thus thought isn’t just a function of hosting brain activity, but hosting brain activity in a certain kind of context. And why can’t this context be partly characterized by modal characteristics, so that although both the animal and the person have the same brain activity, they provide a different modally characterized context for the brain activity, in such a way that only one of the two thinks?

This one-thinker colocationism can be either naturalistic or dualistic. On the dualistic version, we might suppose that the nonphysical mental properties belong to only one member of the pair of associated beings. On the naturalistic version, we might suppose that what it is to have a mental property is to have a physical property in a host with appropriate modal properties—the ones the person, the derson and the chimperson all have.

I think there is one big reason why a colocationist may be suspicious of this view. Ethologists sometimes explain animal behavior in terms of what the animal knows, is planning, and more generally is thinking. These explanations are all incorrect on the view in question. But the one-thinker co-locationist has two potential answers to this. The first is to weaken her view and allow animals to think, but not consciously. It is only the associated non-animal that has conscious states, that has qualia. But the conscious states need not enter into behavioral explanations. The second is to say that the scientists’ explanations while incorrect can be easily corrected by replacing mental properties with their neural correlates.

Of snakes and cerebra

Suppose that you very quickly crush the head of a very long stretched-out serpent. Specifically, suppose your crushing takes less time than it takes for light to travel to the snake’s tail.

Let t be a time just after the crushing of the head.

Now causal influences propagate at most at the speed of light or less, the crushing of the head is the cause of death, and at t there wasn’t yet time for the effects of the crushing to have propagated to the tip of the tail. Furthermore, assume an Aristotelian account of life where a living thing is everywhere joined with its form or soul and death is the separation of the form from the matter. Then at t, because the effects of crushing haven’t propagated to the tail, the tail is joined with the snake’s form, even though the head is crushed and hence presumably no longer a part of the snake. (Imagine the head being annihilated for greater clarity.)

Now as long as any matter is joined to the form, the critter is alive. It follows that at time t, the snake is alive despite lacking a head. The argument generalizes. If we crush everything but the snake’s tail, including crushing all the major organs of the snake, the snake is alive despite lacking all the major organs, and having but a tail (or part of a tail).

So what? Well, one of the most compelling arguments against animalism—the view that people are animals—is that:

1. People can survive as just a cerebrum (in a vat).

2. No animal can survive as just a cerebrum.

3. So, people are not animals.

But presumably the reason for thinking that an animal can’t survive as just a cerebrum is that a cerebrum makes an insufficient contribution to the animal functions. But the tail of a snake makes an even less significant contribution to the animal functions. Hence:

4. If a snake can survive as just a tail, a mammal can survive as just a cerebrum.

5. A snake can survive as just a tail.

6. So, a mammal can survive as just a cerebrum.

Objection: Only physical effects are limited to the speed of light in their propagation, and the separation of form from matter is not a physical effect, so that instantly when the head is crushed, the form leaves the snake, all at once at t.

Response: Let z be the spacetime location of the tip of the snake’s tail at t. According to the object, at z the form is no longer present. Now, given my assumption that crushing takes less time than it takes for light to travel to the snake’s tail, and that in one reference frame w is just after the crushing, there will also be a reference frame according to which z is before the crushing has even started. If at z the form is no longer present, then the form has left the tip of the tail before the crushing.

In other words, if we try to get out of the initial argument by supposing that loss of form proceeds faster than light, then we have to admit that in some reference frames, loss of form goes backwards in time. And that seems rather implausible.

Another argument that we likely start small

In a number of recent posts, I argued that mid-sized objects like ourselves start microscopic. All my arguments so far relied on relativity. Here is one that doesn’t.

1. Biological entities are unlikely to have a perfectly flat macroscopic geometrical face (biological things tend to be rounded, rough, pointy, but not perfectly flat).

2. We are four-dimensional.

3. We are biological entities.

4. If we don’t start microscopic and we are four-dimensional, then we have a perfectly flat macroscopic geometrical face at our temporal beginning.

5. So, probably, we start microscopic.

Why the restriction to macroscopic faces? Two reasons. First, if space is discrete and grid-like, then it may be that all objects have perfectly flat sides at the grid-spacing level. Second, if we are made of point particles, then our geometry likely includes perfectly flat triangles between three outer point particles.

Gaining and losing personhood?

1. Love (of the relevant sort) is appropriately only a relation towards a person.

2. Someone appropriately has an unconditional love for another human.

3. One can only appropriately have an unconditional R for an individual if the individual cannot cease to have the features that make R appropriate towards them.

4. Therefore, at least one human is such that they cannot cease to be a person. (1–3)

5. If at least one human is such that they cannot cease to be a person, then all humans are such that they cannot cease to be a person.

6. If all humans are such that they cannot cease to be a person, then it is impossible for a non-person to become a human person.

7. All humans are such that they cannot cease to be a person. (4,5)

8. It is impossible for a non-person to become a human person. (6,7)

9. Any normal human fetus can become a human person.

10. Therefore, any normal human fetus is a person. (8,9)

(I think this holds of non-normal human fetuses as well, but that’ll take a bit more argument.)

It’s important here to distinguish the relevant sort of love—the intrinsically interpersonal kind—from other things that are analogously called love, but might perhaps better be called, say, liking or affection, which one can have towards a non-person.

I think the most controversial premises are 2 and 9. Against 2, I could imagine someone who denies 7 insisting that the most that is appropriate is to love someone on the condition of their remaining a person. But I still think this is problematic. Those who deny 7 presumably do so in part because they think that some real-world conditions like advanced Alzheimer’s rob us of our personhood. But now consider the repugnance of wedding vows that promise to love until death or damage to mental function do part.

Standing against 9 would be “constitution views” on which, normally, human fetuses become human animals, and these animals constitute but are not identical with human persons. These are ontologies on which two distinct things sit in my chair, I and the mammal that constitutes me, ontologies on which we are not mammals. Again, this is not very plausible, but it is a not uncommon view among philosophers.

Another argument for animals in heaven

1. All embodied humans are animals.

2. Some embodied humans will be in heaven.

3. So, there are animals in heaven.

But of course given the subject heading, you were likely interested whether there are non-human animals in heaven. That, too, can be argued for on the basis of the fact that we are animals.

4. The complete fulfillment of an animal requires it to be in an appropriate ecosystem.

5. Humans are animals.

6. An ecosystem appropriate to humans includes plants and non-human animals.

7. After the resurrection, the human beings in heaven will be completely fulfilled.

8. Thus, the human beings in heaven will be among plants and non-human animals.

Cerebrums and rattles

Animalists think humans are animals. Suppose I am an animalist and I think that I go with my cerebrum in cerebrum-transplant cases. That may seem weird. But suppose we make an equal opportunity claim here: all animals that have cerebra go with their cerebra. If your dog Rover’s cerebrum is transplanted into a robotic body, then the cerebrumless thing is not Rover. Rather, Rover inhabits a robotic body or that body comes to be a part of Rover, depending on views about prostheses. And the same is true for any animal that has a cerebrum.

It initially seems weird to say that some animals can survive reduced to a cerebrum and others cannot. But it’s not that weird when we add that the ones that can’t survive reduced to a cerebrum are animals that don’t have a cerebrum.

The person who thinks survival reduced to a cerebrum is implausible for an animal might, however, say that this is what’s odd about it. An animal reduced to cerebrum lacks internal life support organs (heart, lungs, etc.) It is odd to think that some animals can survive without internal life support and others cannot.

But compare this: Some animals can partly exist in spatial locations where they have no living cells, and others cannot. The outer parts of my hairs are parts of me, but there are no living cells there. If my hair is in a room, then I am partly in that room, even if no living cells of mine are in the room. But on the other hand, there are some animals (at least the unicellular ones, but maybe also some soft invertebrates) that can only exist where they have a living cell.

One might object that the spatial case and the temporal case are different, because in the spatial case we are talking of partial presence and in the temporal case of full presence. But a four-dimensionalist will disagree. To exist at a time is to be partly present at that time. So to a four-dimensionalist the analogy is pretty strict.

Finally, compare this. Suppose Snaky a rattlesnake stretched along a line in space. Now suppose we simultaneously annihilate everything in Snaky. Now, “simultaneously” is presumably defined with respect to some reference frame F₁. Let z be a point in Snaky’s rattle located just prior (according to F₁) to Snaky’s destruction. Then Snaky is partly present at z. But with a bit of thought, we can see that there is another reference frame F₂ where the only parts of Snaky simultaneous with z are parts of the rattle: all the non-rattle parts of Snaky have already been annihilated at F₂, but the rattle has not. Then in F₂ the following is true: there is a time at which Snaky exists but nothing outside of Snaky’s rattle exists. Hence Snaky can exist as just a rattle, albeit for a very, very short period of time.

Hence even a snake can exist without its life-support organs, but only for a short period of time.

Animalist functionalism

The only really plausible hope for a materialist theory of mind is functionalism. But the best theory of our identity, materialist or not, is animalism—we are animals.

Can we fit these two theories together? On its face, I think so. The thing we need to do is to make the functions defining mental life be functions of the animal, not of the brain as such. Here are three approaches:

1. Adopt a van Inwagen style ontology on which organisms exist but brains do not. If brains don’t exist, they don’t have functions.

2. Insist that some of the functions defining mental life are such that they are had by the animal as a whole and not by the brain. Probably the best bet here are the external inputs (senses) and outputs (muscles).

3. Modify functionalism by saying that mental properties are properties of an organism with such-and-such functional roles.

I think option 2 has some special difficulties, in that it is going to be difficult to define “external” in such a way that the brain’s connections to the rest of the body don’t count as external inputs and outputs and yet we allow enough multiple realizability to make very alien intelligent life possible. One way to fix these difficulties with option 2 is to move it closer to option 3 by specifying that the external inputs and outputs must be inputs and outputs of an organism.

Options 1 and 3, as well as option 2 if the above fix is used, have the consequence that strong AI is only possible if it is embedded in a synthetic organism.

All that said, animalist functionalism is in tension with an intuition I have about an odd thought experiment. Imagine that after I got too many x-rays, my kidney mutated to allow me exhibit the kinds of functions that are involved in consciousness through the kidney (if organism-external inputs and outputs are required, we can suppose that the kidney gets some external senses, such as a temperature sense, and some external outputs, maybe by producing radio waves, which help me in some way) in addition to the usual way through the brain, and without any significant interaction with the brain’s computation. So I am now doing sophisticated computation in my kidney of a sort that should yield consciousness. On animalist functionalism, I should now have two streams of consciousness: one because of how I function via the brain and another because of how I function via the mutant kidney. But my intuition is that in fact I would not be conscious via the kidney. If there were two streams of consciousness in this situation (which I am not confident of), only one would be mine. And that doesn’t fit with animalist functionalism (though it fits fine with non-animalist functionalism, as well as with animalist dualism, since the dualist can say that the kidney’s functioning is zombie-like).

Given that functionalism is the only really good hope we have right now for a materialist theory of mind, if my intuition about the mutant kidney is correct, this suggests that animalism provides evidence against materialism.

On a twist on too-many-thinkers arguments

One of the ways to clinch a too-many-thinkers argument (say, Merricks’ argument against perdurantism, or Olson’s argument for animalism) is to say that the view results in an odd sceptical worry: one doesn’t know which of the many thinkers one is. For instance, if both the animal and the person think, how can you know that you are the animal and not the person: it seems you should have credence 1/2 in each.

I like too-many-thinkers arguments. But I’ve been worried about this response to the sceptical clinching: When the animal and the person think words like “I am a person”, the word “I” refers to the person, even when used by the animal, and hence both think the truth. In other words, “I” means something like: the person colocated with the the thinker/speaker.

But I think I have a good response to this response. It would be a weird limitation on our language if it did not allow speaker or thinker self-reference. Even if in fact “I” means the person colocated with the the thinker/speaker, we should be able to stipulate another pronoun, “I*”, one that refers just to the thinker/speaker. And it would be absurd to think that one not be able to justifiably assert “I* am a person.”

Surviving furlessness and inner earlessness

If we are animals, can we survive in a disembodied state, having lost all of our bodies, retaining only soul or form?

Here is a standard thought:

1. Metabolic processes, homeostasis, etc. are defining features of being animals.

2. In a disembodied state, one cannot have such processes.

3. Something that is an animal is essentially an animal.

4. So something that is an animal cannot survive in a disembodied state.

But here’s a parody argument:

5. Fur and mammalian inner ear bones (say) are defining features of being mammals.

6. In a furless and internally earless state, one cannot have such structures.

7. Something that is a mammal is essentially a mammal.

8. So something that is a mammal cannot survive in a furless and internally earless state.

I think 5-7 are no less plausible than 1-3. But 8 is clearly false: clearly, it is metaphysically possible to become a defective mammal that is furless and internally earless.

The obvious problem with 5, or with the inferences drawn from 5, is that what is definitory of being a mammal is being such that one should to have fur and such-and-such an inner ear. The same problem afflicts 2: why not say that being such that one should have these processes and features is definitory of being a mammal.

Cerebrums, animalism and teleology

Suppose you are essentially an animal. If your cerebrum were transplanted into a vat and the rest of your body—including, of course, the brain-stem—were to maintain circulation, nutritive functioning, muscle tone and so on, where would you go? Would you go with the cerebrum in the vat, with the rest of the body, or would you be just plain dead?

Here’s a line of thought. There are more primitive animals that don’t have a cerebrum, but still have a circulatory system, a nutritive system, etc. Thinking about these animals makes on think that the survival of an animal has to do with maintenance of the lower level homeostatic functions. So, we go with the parts of the body responsible for such things.

But an Aristotelian animalist can resist the analogy to primitive animals on teleological grounds. For instance, our circulatory system’s physical resemblance to the circulatory systems of primitive animals misses out on a crucial metaphysical difference: our circulatory system has the support of the life of the mind as its central telos, and it supports the life of the mind by supporting the cerebrum. The teleological structure of primitive animals and human animals is different: functions that are close to the teleological center of the life of a primitive animal are further from the teleological center of human life. It may be the case that when an animal is divided, it goes with the parts that are teleologically more central. If so, then in the initial thought experiment, you would go with the cerebrum.

[By the way, this post represents a new workflow. I am using John MacFarlane pandoc, writing the post as a text file, and then running a script that does pandoc -S filename | iconv -f utf-8 -t utf-16le | clip and pasting it in. This should make math less painful to type.]

Our canine pets are animals, so we are animals

1. Our canine pets are primary bearers of their mental states.
2. Our canine pets are higher mammals.
3. So, some higher mammals are primary bearers of their mental states. (1 and 2)
4. Either (a) all higher mammals are primary bearers of their mental states or (b) no higher mammals are primary bearers of their mental states.
5. Human animals are higher mammals.
6. So, human animals are primary bearers of their mental states. (3, 4, 5)
7. We are primary bearers of our mental states.
8. If we are not human animals, then it is not both the case that we are primary bearers of our mental states and human animals are primary bearers of their mental states.
9. So, we are human animals. (6, 7, 8).

Premise 1 holds because the master-pet relationship to a canine pet while not being interpersonal (since dogs are not persons) has the kind of intimacy that requires the relata to be primary things with minds.

In correspondence, Jeff McMahan denied that our canine pets are animals. He held that our canine pets are not dogs but are rather constituted by dogs, much as he holds that we are not human animals but are rather constituted by human animals. So McMahan will deny premise 2. But I think premise 2 is obviously true.

The remaining controversial premise is 4, which holds that all higher mammals are on par with regard to whether they are primary bearers of their mental states. But I think 4 is highly plausible in light of the similarities between the brains and behavior of higher mammals.

I thank Allison Thornton for helping me work out this argument.

If birds aren't reptiles, maybe people aren't animals?

Some biological taxa are clades: a clade is a taxon that contains a descendant of every included organism. For instance Mammalia is a clade, while Reptilia is not, since birds aren't reptiles but are descendants of reptiles. There are biologists that wish that we used a phylogenetic classification scheme, one where all taxa are clades. But that's not what is traditionally done. Let's consider the hypothesis that the traditional approach is right in the sense that it cuts nature at joints. Then a taxon can change from being a clade to being a non-clade. I assume that Reptilia changed in this way when birds evolved. And whether such a change has occurred is a substantive question.

In principle, then, it is possible for the kingdom Animalia, which I understand is normally taken to be a clade, to change into a non-clade. And it is a substantive question, then, whether such a change occurred when humans evolved. It could be the case that sapience marks such a departure that we are a new kingdom, and Animalia is no longer a clade. I think a close relative of this thought--albeit without evolutionary connections--is behind the ordinary person's (as opposed to a philosopher's) resistance to the idea that we are animals: personhood is such a transformative feature that it marks a completely new kind of organism.

But while the question is substantive, it's not tenable to say we aren't animals. If we are not animals, it seems we aren't mammals. (Maybe more can be said, though?) But if we aren't mammals, then various natural kind-based explanations fail: we can't say, for instance, that we have complex bones in the inner ear because we have mammals.

Note, too, that the question raised in this post is orthogonal to the question that animalists are concerned with. For all that we animalists need for our positive theory is that we are organisms--whether the particular kind of organism we are is an animal, a plant, a fungus or something else is not very important for the theory.

Animalism

I just had a really naive thought. Let's imagine what a definition of animals would be like. It would say something like this: Animals are things that maintain homeostasis, take in nutrients and grow, reproduce, initiate and control a large variety of types of motion in response to changing environmental features, etc. It's not very easy to come up with details of the definition, but it seems like it would go something like this. Well, it's pretty clear that we do these things, as well as doing any plausible items we'd want to add to the definition. So we're animals. Case closed.

What could an anti-animalist say? I guess her best hope would be: The definition is close to the truth, but not quite. Rather, animals are things that non-derivatively maintain homeostasis, take in nutrients and grow, etc., etc. But it seems to me that there is a natural dilemma. Derivative homeostasis (say) either is or is not a case of homeostasis. If it is, that seems all we need for animalhood (along with analogous other qualities). If it is not, then the anti-animalist can't say that we have homeostasis, and that's absurd.

Brains and animalism

Animalists hold that we are animals. It is widely accepted by animalists that if a brain were removed from a body, and the body kept alive, the person would stay with the bulk of the body rather than go with the brain.

I wonder how much of the intuition is based on irrelevant questions of physical bulk. Imagine aliens who are giant brains with tiny support organs—lungs, heart, legs, etc.—dwarfed by the brain. I think we might have the intuition that if the brain were disconnected from the support organs, the animal would go with the brain. In the case of beings that dwarf their brains, it feels natural to talk of a certain operation as a brain transplant. But in the case of beings that are almost all brain, the analogous operation would probably be referred to as a support-system transplant. Yet surely we should say exactly the same thing metaphysically about us and the aliens, assuming that the functional roles of the brains and the other organs are sufficiently similar.

This isn't a positive argument that we'd go with our brains. It's just an argument to defuse the intuition that we wouldn't.

What about cerebra? Here's a widely shared intuition. If the cerebrum is removed from the skull of an animal and placed in a life-support vat, the animal stays with the rest of the body.

But now suppose that we granted that the animal goes with the whole brain. Let's say, then, that I am an animal and sadly become a brain in a life-support vat, losing the rest of my body. Suppose that next my brain is cut and the upper and lower brains are placed in separate life-support vats. It does not seem particularly plausible to think that the animal goes with the lower brain. (Maybe the animal dies, or maybe it goes with the upper brain.) So once we've granted that the animal would go with the brain, the primacy of the lower brain for animal identity seems somewhat undermined.

Maybe, though, one could accept both (a) the common intuition that if the cerebrum were removed the human animal would go with the rest of its body, and (b) my intuition that if the human animal were first reduced to a brain, and the brain then cut into the cerebrum and lower brain, the animal would go with the cerebrum. There is no logical contradiction between these two intuitions. Compare this. I have a loaf of bread. Imagine the loaf marked off into five equally sized segments A, B, C, D and E. If I first cut off the 2/5 of the loaf marked D and E, it's plausible that the loaf shrinks to the ABC part, and DE is a new thing. And then if I cut off C, the same loaf shrinks once again, to AB. On the other hand if I start off by cutting off the AB chunk, the loaf shrinks to CDE. So the order of cutting determines whether the original loaf ends up being identical to AB or to something else. (We can also make a similar example using some plant or fungus if we prefer a living example.) Likewise, the order of cutting could determine whether the animal ends up being just a cerebrum (first remove brain, then cut brain into upper and lower parts) or whether it ends up being a cerebrumless body.

We might have a rough general principle: The animal when cut in two tends to go with the functionally more important part. Thus, perhaps, when the human animal is cut into a brain and a rest-of-body, it goes with the brain, as the brain is functionally more important in the brainier animals. When that brain is subsequently cut into upper and lower brains, the brainy animal goes with the upper brain, as that's functionally more important given its distinctively brainy methods for survival. On the other hand, if the human animal is cut into a cerebrum and a cerebrumless-rest-of-body, perhaps (I am actually far from sure about this) the animal goes with the cerebrumless-rest-of-body, because although the upper brain is more important functionally than a lower brain, the lower brain plus the rest of the body are collectively more important than the upper brain by itself. So the order of surgery matters to identity.

The human animal and the cerebrum

Suppose your cerebrum was removed from your skull and placed in a vat in such a way that its neural functioning continued. So then where are you: Are you in the vat, or where the cerebrum-less body with heartbeat and breathing is?

Most people say you're in the vat. So persons go with their cerebra. But the animal, it seems, stays behind—the cerebrum-less body is the same animal as before. So, persons aren't animals, goes the argument.

I think the animal goes with the cerebrum. Here's a heuristic.

• Typically, if an organism of kind K is divided into two parts A and B that retain much of their function, and the flourishing of an organism of kind K is to a significantly greater degree constituted by the functioning of A than that of B, then the organism survives as A rather than as B.

Uncontroversial case: If you divide me into a little toe and the rest of me, then since the little toe's contribution to my flourishing is quite insignificant compared to the rest, I survive as the rest. More controversially, the flourishing of the human animal is to a significantly greater degree constituted by the functioning of the cerebrum than of the cerebrum-less body, so we have reason to think the human animal goes with the cerebrum.

Another related heuristic:

• Typically, if an organism of kind K is divided into two parts A and B that retain much of their function, and B's functioning is significantly more teleologically directed to the support of A than the other way around, then the organism survives as A rather than as B.

My heart exists largely for the sake of the rest of my body, while it is false to say that the rest of my body exists largely for the sake of my heart. So if I am divided into a heart and the rest of me, as long as the rest of me continues to function (say, due to a mechanical pump circulating blood), I go with the rest of me, not the heart. But while the cerebrum does work for the survival of the rest of my body, it is much more the case that the rest of the body works for the survival of the cerebrum.

There may also be a control heuristic, but I don't know how to formulate it.

Transgender realism, abortion, animalism and colocationism

There are two major families of views on our relationship to the biological world. On animalism, we are animals of the species homo sapiens. Animalism comes in two varieties: physicalist animalism says that we are purely physical animals and dualist animalism says that some or all animals, including all of us, have non-physical features such as non-physical mental states or a soul (of a Cartesian or an Aristotelian sort). On colocationism, wherever one of us is present, there is an animal of the species homo sapiens present as well, but we are not identical to such an animal. There are multiple varieties of colocationism. On the constitution view, we are wholly constituted by our associated animals. Typically, such constitution theorists are physicalists—the animals are purely physical and hence so are we. The other main variety of colocationism is further-aspect dualist colocationism on which our associated animals are purely physical, but we are not. This includes a view on which we are souls (which count as located wherever the ensouled bodies are), a view on which we are a composite of an animal and a soul and a view on which we are partly constituted by an animal and partly constituted by a non-physical aspect. The debate on animalism versus colocationism is thus to a significant degree orthogonal to the debate between physicalists and dualists.

If animalism is true, then a normal adult, say Sally, used to be a fetus, and to have killed that fetus would have been to kill Sally, and it would have deprived Sally of even more than killing Sally now would. Thus, animalism strongly suggests that abortion is wrong, though violinist-type arguments could be used to try to resist that conclusion. On the other hand, colocationist views are much more congenial to pro-choice philosophers, and hence appear to be somewhat dominant in the pro-choice moral philosophy scene. For if colocationism is true, then it could be that the human animal existed significantly before Sally came to be colocated with it, and if so, then killing that human animal in abortion would not have been a killing of Sally. Though, a colocationist could also think that colocation started at fertilization and hence a killing of the fetus would also be a killing of the colocated Sally.

So whether animalism or colocationism is the right metaphysics of us is very relevant to the moral status of abortion.

Now I will cautiously wade into waters that are rather unfamiliar to me, and I apologize if I use terminology in non-standard ways. The question of animalism versus colocationism appears to be very relevant to the question of transgender realism. Let Type I Transgender Realism (1TR) be the view that some people literally are men in female bodies or women in male bodies. Let Type II Transgender Realism (2TR) be the claim that some people who had female bodies and felt that they were or should be men are now, after gender reassignment surgery and hormonal treatment, literally men, and some people who had male bodies and felt that they were or should be women are now, after gender reassignment surgery and hormonal treatment, literally women. If 1TR is true, so is 2TR: surely a man in a female body does not cease to be a man after the body is surgically modified to be more male-like. But at the same time, the law in a number of jurisdictions tracks 2TR but not 1TR, requiring surgery for legal classification as male or female.

Now, it seems very plausible that whether a human animal is male or female (or hermaphrodite) depends on biological criteria very much like those by which we ask whether an elephant or a gecko or maybe even a plant is male or female (or hermaphrodite). These criteria do not depend on psychological states but on whether the organism is such that it should produce its own sperm or such that should produce its own eggs (or both). It is also very plausible that men are male (though they may be more or less feminine) and women are female (though they may be more or less masculine). So if we are human animals, then whether we are male or female, and hence whether we are men or women, depends solely on biological criteria, and 1TR is false.

Moreover, if we are human animals, then 2TR is also false, at least given the current surgical methods. If we remove a mouse's female reproductive system and reshape what remains to look like male genitalia, and treat with hormones, what we have is a female mouse that has lost its reproductive system and behaves like a male. It might be more complicated if a functioning male reproductive system is transplanted. But I think it would still be true that the resulting mouse isn't such that it should produce sperm. Moreover, the mouse doesn't produce its own sperm—it produces the donor's sperm. Here's another route to the conclusion that even a functioning male reproductive transplant doesn't turn the female mouse male. After mere removal of a female (respectively, male) mouse's reproductive system, what we have is a female (respectively, male) mouse that is missing a reproductive system. But now imagine two identical twin female mice, A and B. Both have their female reproductive systems removed. But B then has a male reproductive system added, and then removed. If B became male upon addition of the male reproductive system, then B should still be male after removal thereof—a male does not cease to be a male after losing the reproductive system, but becomes a mutilated male. But A and B may be exactly alike at the end of suffering all this cruelty. It would then be odd to say that of two exactly similar mice, one is male and one is female. So we should say that they are both female, and hence B was female all along, even while having the male reproductive system.

Maybe an animalist could get out of this argument by distinguishing between sex and gender, and denying the idea that a man is an adult male human and a woman is an adult female human. Instead, perhaps, a man is an adult masculine human and a woman is an adult feminine human. The appeal to non-human animals in my argument then becomes irrelevant because only human animals can be men and women. On this story, there will be a disnalogy between the triple of terms "human", "woman" and "man" and triples like "chicken", "hen" and "rooster". A hen is a female chicken, but a woman need not be a female human. While this animalist-compatible view would let one preserve 1TR and 2TR, it would not be compatible with the aspiration that "a woman in a man's body" may have to be really female. It is my impression it is more the genderqueer than the transgendered who use phrases like "male woman" or "female man". Besides the idea of literally male women and female men seems problematic.

On the other hand, if colocationism is true, it is much easier to hold to 1TR and 2TR. Sure, Sally's associated animal (the animal that she is partly or wholly constituted by) may be male, but perhaps maleness and femaleness in a human person is not simply determined by whether the human animal is male or female. Colocationism could allow one to hold to 1TR without revisionary biology and without the oddness of saying that Sally is a male woman. Moreover, colocationism makes it plausible that sexual reassignment surgery could be a valuable thing: it is fitting that a man be associated with a male animal and a woman with a female animal, and while my arguments above suggest that surgery will not change the sex of the associated animal, it could somewhat improve the fit between the person and the associated animal.

Of course, colocationism by itself does not imply 1TR or 2TR: one could still think that a person is a man if and only if the person is associated with an adult male human animal and that a person is a woman if and only if the person is associated with an adult female human animal. But colocationism opens options beyond that.

So the debate between animalism and colocationism is not only highly relevant to the abortion debate but also to the question of transgender realism. Settling the question between the animalists and colocationists would not completely settle the latter two questions, but it would lead to significant progress.

Let me end by saying, without argument, that we are primates and all primates are animals. Hence animalism is true.

Long snakes and Relativity Theory

This is an exercise in some rather gruesome metaphysics of parthood. If you don't like gruesome examples, stop reading. There will be a payoff, though--a defense of animalism.

Imagine a long snake, all stretched out, and for simplicity assume uniform linear mass distribution. Let's say the length of the snake is 10 meters and its diameter is 0.1 meters. Suppose that something cuts off the rear 1/4 of the snake, and the cut happens at near-light speed--maybe a blade descends on the poor snake at 90% of the speed of light. Suppose that almost instantaneously before the blade touches the unfortunate snake, a butterfly almost instantaneously brushes its wing against the tip of the snake's tail and never has any other contact with the snake or its bits. (Let's say "almost instantaneously" means "in the amount of time during which light travels 0.01 meters.) Then, it seems, butterfly touched the snake. Call the reference frame in which the above description takes place "frame A". But, it is a fact that then there is a reference frame, call it "frame B", in which when the butterfly touched the snake, the tail was already cut off. It seems that in this reference frame, the butterfly did not touch a (or the) snake--he merely touched a cut-off tail.

It follows that the following propositions cannot all be true:

1. In frame A, the butterfly touched the snake.
2. In frame B, the butterfly did not touch the snake.
3. Whether two substances touch does not depend on the reference frame.

So we must deny at least one of (1), (2) or (3). Note that affirming (1) and (2) and discarding (3) would have the interesting consequence that whether battery has been committed depends on the reference frame. For suppose that an accident cuts off my leg at near light speed. Then there can be a situation where you very quickly mutilate the "foot" at the end of that leg (I put it in quotation marks, because there is an issue whether a disconnected foot is a foot) just before the leg is cut off. By exactly the same reasoning, then, in one reference frame it seems you've committed battery--you've mutilated a part of me--and in another you haven't. (In neither reference frame do I feel the mutilation, because the leg is cut off before the nerve signals come from the "foot" to my central nervous system.) I don't think whether battery has been committed should differ between reference frames. (Would you be guilty in one frame and innocent in another?)

So, I need to reject either (1) or (2) or both. It seems to me that (1) is harder to deny than (2). To deny (1) we would have to allow that the tail is fully connected to the snake, and yet not a part of it because it is about to be cut. So, we should deny (2). Hence, something can be a part of a body even though it is already severed from the body.

How long can this weird state of affairs go on? I don't really know. We could say that it goes on until the part is severed in all reference frames. But while that is an attractive idea, it neglects the fact that we are talking about organic parts, and what matters here is organic connections, not relativistic connections. The relevant scale of velocities is the speed of the fastest organic signals, not the speed of light. Suppose that the snake's brain sent a nerve signal to the tip of the tail, and the nerve signal passed the cut-point just before the cutting began. Because nerve signals move much slower than light, before the nerve signal arrives at the tip of the tail, it will already be the case that in all reference frames the tail is severed. Still, I think the tail might count as part of the snake, as long as the signal is traveling there. Let's say the signal tells the tip of the tail to wiggle. Maybe we can say that while the tail yet wiggles under the influence of that nerve signal, the tail is a part of the snake.

Does any of this matter, except as abstruse metaphysics? Maybe. Take animalism, the theory that you and I are animals. A standard objection to animalism is that we can survive as brains in a vat, but a brain in a vat is not an animal. However, the above considerations suggest that, at least for more complex beasts like snakes and humans, connection to the nervous system has a relevance to determining what still is and what no longer is a part of the body. The nervous system, then, has a kind of centrality in more complex animals from the organic point of view. And this makes it plausible the animal could survive as an organism when pared down to just a nervous system, assuming appropriate life-support mechanisms. And it is not a far leap from that to suppose that we can survive as organisms with just central nervous systems, and maybe even with just the central part of the central nervous system, namely the brain (in a vat, of course).

Now, if animalism is true, then we were all once fetuses--I was the numerically same organism as a fetus. Thus, a human fetus is one of us, and presumably killing it is wrong. Thus, we have here a loose line of argumentation from Relativity Theory to the wrongness of abortion. Isn't philosophy fun?