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...

Yes it is. But now I suppose you expect me to say how. You are asking a lot. Here are a few tips. (1) Look for a question that is small but not trivial. It’s often a good idea to look for a question that is about a specific argument for a big claim, rather than a question directly about the big claim itself. This gives you focus and specificity. It also gives you automatic structure, since it gives you the distinction between the issue of whether the premises are acceptable and the issue of whether the conclusion follows from the premises. (2) Look for a question that is relatively clear (though you may still need to spend a lot of effort making it clearer). (3) Look for a question that immediately suggests different readings that you can distinguish. More generally, look for a question that will enable you to make useful distinctions. (4) Look for a new question that looks like an old question that...

This is an excellent question, but one of the reasons it is not easy to answer is that we are not comparing like with like, because different senses give us information about different kinds of thing. It’s not like two people who tell you about astronomy where we might say that one person is more credible than the other on the same subject. Take sight and taste. Sight seems to give more information about the external world, but in part for that very reason it is more open to error. Taste seems to give much more restricted and subjective information, and in part for that very reason it is less open to error. Having said that, however, all the senses may form the basis for inferences about what is going on in the external world, and any of these inferences may go wrong. Another reason your question is hard is that philosophers don’t agree about what counts as the senses getting things right. Take the colors that we believe things to have on the basis of sight. Some philosophers think that...

You could have had lots of conscious experiences yesterday that you forget today. What makes an experience conscious is its character at the time, not the traces it leaves in memory. This raises the tantalising question of how you know that you haven’t had all kinds of wild experiences in the past that that you have forgotten. This is an interesting inversion of more familiar sceptical arguments, which tend to assume that we do know about our experiences but question how we can know what caused them.It seems clear that I do have reason to believe that I have had some experiences I now forget. After all, I have reason to believe that my memory is very imperfect. For example, I have reason to believe that I had many more experiences as a child than I can now recall. At the same time, there are lots of crazy possible experiences that I have reason to believe I never had. In many cases, the fact that I don’t remember having an experience makes it pretty likely that I didn’t have...

Moral questions typically have an empirical component. For example, the question whether we have an obligation to paint all the roofs in the world white depends in part of the question whether doing this would reduce global warming, and that is an empirical question. And as Miranda Fricker points out, if utilitarianism is correct, then you can work out what is right across the board by answering the empirical question of what would generate the most happiness. But the question whether utilitarianism (or pretty much any other ethical theory) is correct does not seem to be an empirical question. What experiment would help? So while applying an ethical theory to determine what is right may depend on empirical evidence, testing and ethical theory does not seem to be an empirical matter. The empirical facts only seem to take us so far when it comes to determining what we ought to do.

I would distinguish the question why you do things you should not do from the question why you do things you do not want to do. Both are interesting, but the first one seems easier to answer. It's just that sometimes you don't want to do what you should do. That may happen for various reasons. Maybe you don't know what you should do or maybe what you should do involves helping other people but you are selfish. And even if you recognise that there is something you should do for your own good you may just not want to do it. I know that I should floss every day, but I don't do it because I don't want to. The second question is harder to answer. How can you do something you don't want to do? Of course maybe someone is forcing you to do it, but that is not what you have in mind. Nobody is keeping me from flossing, and suppose now that I really do want to floss, because I really do want to take care of my teeth, but still I don't do it. This is weakness of the will. The...

Almost everything we know we only know with the help of what others have told us. In that sense, testimony is our dominant source of knowledge. So it is somewhat surprising that the history of epistemology contains so little material on the epistemology of testimony. One reason for this neglect is the view that belief from testimony is fundamentally less secure than belief from reason or direct experience. Another is the view that, however important testimony may be, it is never the source of new knowledge, but only a way of distributing old knowledge. Both of these views are eminently disputable. One famous discussion of the epistemology of testimony is David Hume's chapter On Miracles in his Inquiry Concerning Human Understanding . For a good recent book, have a look at Tony Coady's Testimony.

There are several different questions you may be raising here. One is how we can imagine something that doesn't exist, like a unicorn: aren't we then saying the same thing is both real and unreal? The short answer is that they are not the same thing: unicorns are not real, but imaginative experiences of unicorns are. Another question is how a physical brain can contain or even generate experiences. This is the general mind-body problem: a tough nut to crack. And there is also a third question. Even if we don't worry about how the mind can have experiences when there is an external cause -- say the experience of a horse when we look at one -- we might worry about how it has the power to generate an experience of something is has never seen, like a unicorn: where does this content come from? This too is an interesting question. Some philosophers answer that we make things up in our imagination by putting together bits and pieces of what we have seen -- say combining the general shape of a horse with the...

Nobody thinks that you always want whatever happens to you. I really didn't want to stub my toe earlier today (not even subconsciously), and I think that you can daydream without wanting to. But these are cases where we don't choose. The harder question you are asking is whether there are any cases where we do choose, but what we choose is not what we want. Well, take the reluctant drug user. He chooses the drug because of his addiction, but he also wants not to take the drug. Still, some philosophers say that he must have wanted the drug more than he wanted not to take it. But others say that insofar as what happened was determined by his addiction, it wasn't really a choice but more like the daydreaming case: something that happens to the addict but not something that he chose. And yet others would say that taking the drug was a real choice, but the reluctant addict nevertheless wanted not to take it more than he wanted to take it. Coercion and weakness of the will tie philosophers up in knots.

I'm a little bit worried about Australia, but let's leave that continent to one side. Sometimes what makes something a particular kind of thing is a set of superficial properties, while in other cases the relevant properties are less obvious. Island is in the former group, dog is the in the latter. Presumably what makes something a dog has something to do with its genetic makeup, not superficial properties like its bark. In a way, this is surprising, since we talked about dogs before we know anything about genes, and even today I talk confidently about dogs without knowing how they differ genetically from cats. But Saul Kripke and Hilary Putnam have given plausible accounts of how this is possible. Imagine someone who wanted to introduce a name for a biogical kind nobody had named before. It might be someone who sees member of an exotic new species of animal. She could point to some members of that species and say something like, 'let's call that animal and every other animal of the same species a...