I went to a lecture at the LSE recently on the life and work of Philippa Foot. It was a very nice event, describing the life of a thoughtful daughter from an aristocratic family and how its events – including those surrounding the Second World War – led her to the philosophical problems with which she was chiefly concerned.
The main topics under discussion were moral relativism and the question, "Why be moral?" Professor Sarah Broadie gave an outline of how Foot's answer developed, in which she eventually arrived at the notion that there are certain universal and basic human needs, whose fulfillment leads to flourishing and long-term survival. This view of morality as fulfillment of intrinsic needs or goals, or needs which arise as part of the logic of the situation, still seems easy to pick apart. One need only find examples of actions that are intuitively morally impermissible and yet cohere with a long-term survival strategy – for instance, a medical procedure that causes extreme and unnecessary pain, but also wipes the patient's memory of it completely, without fail, after the operation has finished.
Perhaps those are just so many details to be ironed out. I had a more skeptical concern. Even if there are these intrinsic needs, what is good about fulfilling them? Why is it good to survive and flourish in the first place? The speakers' answer was essentially that Foot did not address this sort of question in her work; her interest was in finding "where the trouble is" – where our moral intuitions conflict and why. (Question and discussion here from 68:00.)
One way to respond to the question could be this. Ethics is an intellectual pursuit, a field of knowledge, whose theories can be better or worse (as per various criteria, with some normative theories imposing a very specific set of criteria, some of which we all agree on, such as non-contradiction). Since morality is about what we should do, by definition we should act in accordance with the best available theory.
I think this is unlikely to satisfy the skeptic. He could concede that one moral theory is better than a rival theory that is riddled with contradictions. But this says no more about the objectivity of ethics than about the existence of fairies at the bottom of the garden – about which there could equally well be better and worse theories. It is a sort of ontological argument for the existence of morality.
Is skepticism self-defeating?
The conjecture our skeptic disputes is that it is good to survive and flourish. If he simply says, "That's rubbish," and ends the discussion, that is of course his prerogative. But if he wants to continue to argue about it, the view that it is not good to survive and flourish quickly becomes untenable, for the following reason. Taking this view seriously, we would stop trying to survive and flourish. We might die out as a species, or at any rate there would be fewer of us, and we would be less productive. Yet criticism and improvement of the theory that it is not good depends upon people being around and disposed to work on it. So the skeptic, taking his view seriously, destroys the means by which his own opinion might be proved wrong. Inherently, this view is incompatible with truth-seeking. The question that then arises is: "Why be truth-seeking?"
It seems to me that certain assumptions are made by the nature of the topic and the conversation itself. Firstly, one cannot get away with saying "I take no position on whether or not it's good to survive, flourish or be truth-seeking," because it is either good or not, and one's actions necessarily assume and express a position on it. Regardless of what the skeptic says or is aware of believing, not striving to survive, etc., implies that he does not think it is good. Secondly, by taking up a view and advocating it as true, the skeptic takes for granted that he and others should hold true theories – that we should be truth-seeking. Yet we've determined that his answer to the moral question is not truth-seeking. For this reason, any claim that it is not good to survive and flourish is ultimately self-contradictory.
Unlike the 'ontological' argument, this is not a completely a priori proof of objective morality, although I suspect it has some related problem. Perhaps it tries to be an argument without being an explanation. But I can't find any specific fault with it.