I read that an artery is a blood vessel that carries blood away from the heart. However, a dead body still has arteries, and they don't carry blood anywhere anymore. Moreover, there may be dead or non functioning arteries within a living body. A friend of mine suggests that an artery is a blood vessel that evolved to carry blood away from the heart, but a creationist wouldn't believe her, and I would prefer a definition of "artery" that could be accepted by anyone. Could you, philosophers, provide such a definition?

Your question relates directly to a central issue in the philosophy of biology, which is how to understand what it means to say that a biological trait has a particular function. The appeal to evolution by natural selection is attractive here because we often seem to explain why a trait is present by appeal to its function, and this practice would otherwise be strange, since functions are effects and we don’t normally take effects to explain their causes. Thus suppose we say ‘We have arteries because they carry blood away from the heart’. Carrying blood away from the heart is an effect of having arteries, so how can it explain why we have them? But in the context of natural selection, we can say that it is because arteries in our ancestors carried blood in the past that we are here now, arteries and all. So the functional explanation ‘We have arteries because they carry blood away from the heart’ is actually not an ‘effectal’ explanation, but a causal explanation. What...

I have a question/argument that straddles the free will debate, philosophy of mind and evolution. I hope it is not too bad. Suppose all of our actions are determined by the conjunction of natural laws and the history of the world and thereby we are deeply misguided in our view of ourselves as free, autonomous beings. My question is then, from an evolutionary perspective, why would we evolve to have this illusion about ourselves? Wouldn't philosophical zombies with no consciousness be simpler entities and thereby more likely to evolve? If consciousness does not really have any causal efficacy (in the libertarian sense), why do we have it?

It is difficult to see why a zombie couldn't do all the behavioural things we do, and indeed just as efficiently and effectively as we do. But that wouldn't show that consciousness could not arise through evolution, since it might be that we do what we do with the help of consciousness. But maybe consciousness doesn't even help us do what we do: it's just a by-product of the way we do what we do. But even in this case, it might arise through an evolutionary process, just like the lub-dub sound of a beating heart. But suppose now that consciousness does play a causal role in the way we do what we do. Is there any reason why the specific consciousness of ourselves as a free agents might arise through natural selection? Well (and here I am just speculating) maybe a creature that feels in control tends to do better in the world, and that feeling of control leads naturally to an idea of free will, even if it turns out that the idea is ultimately incoherent. This takes us back to the by-product...

What is a function (of an object or an idea)? I once read that functions are conventional or "artificial". I can understand that an ashtray has its function (being a place to put cigarette ash) only if we assign it to it, but the function of our hearts (to pump blood) seems quite more natural.

Some objects simply aquire a function in virtue of being used in a certain way, like the rock I use to prop open my office door. But traits of biological organisms do seem to have natural functions, like the white fur of the polar bear, whose function is camoflage. There is a spirited discussion among philosophers of biology over just how to analyse biological functions, but the selected effects account is perhaps the most popular. On this view, an effect of a biological trait is a function if the trait was selected for by natural selection because of that effect. Thus camoflage is a function of white fur because it is in virtue of that effect that polar bears came to have white fur. Notice that not all effects of biological traits qualify as functions on this account. The heart pumps blood, and that is presumably an effect that was selected for and so counts as a function. But the heart also produces that adorable lub-dub sound; that is just as much an effect of the heart, but presumably not the...

Is religion a result of evolution? I mean, is the human kind fitter and more surviving by being religious?

This is a matter of dispute. First of all, there is dispute over whether religion has any innate component, for example whether there is an innate predisposition towards religion. Second, if there is an innate component, there is a further dispute over whether this is present because it is in itself advantageous from a natural selection point of view, or whether instead it is a by-product of other cognitive traits having nothing particular to do with religion that have such an advantage.

If science (i.e. evolutionary psychology) can explain why I have the morality I do, does that mean morality is subjective? If what I believe about morality is just a product of my evolution and my upbringing, can I still expect other people to live up to my principles even though they may have had a different upbringing? What about myself? Can I still hold myself to my own standards or am I being deceived by my evolution into thinking it would be wrong to do so?

It is hard to say what makes a moral judgment correct, but the fact that a belief in a certain area has a innate basis, perhaps molded by evolutionary forces, does not entail that the belief is subjective. Thus it might be that I have an innate belief that certain animals are dangerous, and that this belief is objectively correct. Moreover I might go on to acquire excellent empirical reasons for this belief (if I survive the data).

ID theorists and creationists like to say that the Theory of Evolution is "just a theory." Is that true? What does that mean? What's the difference between "truth" and "theory"?

Theories are descriptions, and they come in two flavors: true and false. So the Theory of Evolution can be both a theory and true, which is just what a great number of scientists believe. When evolution by natural selection is called a theory, however, this is sometimes intended to emphasise that there is no proof that it is true. Now if by 'proof' we mean what pure mathematicians produce, then this is correct. There is no proof of the Theory of Evolution, and there is no proof of any other empirical theory either. Proof in this sense is not an option in science, because all theories go beyond the evidence upon which they are based. There can similarly be no proof that the sun will rise tomorrow. But the sense in which it is true that there is no proof of evolution is compatible with the claim that there is overwhelming evidence that it is true, which is again what a great number of scientists believe.