Edward Skidelsky summarizes Philippa Foot’s argument against the common opposition between what is and what ought to be in an interview with the Browser:
MacIntyre thinks that the notion of virtue has to be detached from Aristotle’s original ‘metaphysical biology’ as he calls it, whereas Philippa Foot thinks that maybe it doesn’t. In Natural Goodness – which is beautifully written, by the way, and one of my favourite works of moral philosophy – she has this interesting discussion of the sentence “human beings have 32 teeth”. This is a perfectly ordinary sentence in English; readily intelligible, the kind we use all the time. But when you think about it, what does it actually mean? Clearly it doesn’t mean, “all humans have 32 teeth”. That would be false. It doesn’t mean, “the average human has 32 teeth”: that would also be false. What it seems to mean is something like: “human beings are meant to have 32 teeth”, or, “if everything goes well for them they should have 32 teeth”. In other words, it is a normative statement, as well as being an ordinary descriptive statement about the species homo sapiens. Foot says that many of the statements we make about species have this odd feature of being both normative and descriptive. She’s attacking the dominant tendency in modern ethics to think of moral values as attitudes on our part, or stances. She says no, they’re facts about our species that we can discover. As to how they’re spelled out in detail – there’s a huge amount of flexibility there. It’s not as if all human beings have to conform to some template. That’s where we differ from other animals. All lions, for example, lead pretty much the same kind of lives. Humans don’t. So clearly a lot depends on choice and culture. But some things are perversions by any standard. Take the Roman habit of leaning over and vomiting on the floor after a meal so that they could carry on eating. I would say that this was a perversion. You’re perverting the natural function of eating, which is to nourish yourself.
Skidelsky, a gifted young British philosopher, has written in our pages on how avarice ceased to be seen as a vice.
Via David Schaengold.