This article is my latest attempt to come up with a minimal version of my evolutionary theory of fairness, previously summarized in my book Natural Justice. The naturalism that I espouse is currently unpopular, but Figure 1 shows that the scientific tradition in moral philosophy nevertheless has a long and distinguished history. John Mackie's Inventing Right and Wrong is the most eloquent expression of the case for naturalism in modern times. Mackie's demolition of the claims made for a priori reasoning in moral philosophy seem unanswerable to me.

We continuously form perceptual beliefs about the world based on how things appear to us in our perceptual experiences. I see that the ripe tomato in front of me is red and I form the belief that this tomato is red based on my seeing it, i.e. based on my veridical perceptual experience of this red tomato. Perceptual experiences and beliefs are representational mental states. Both are defined not by what they are, i.e. their physical properties, but by what they are about, what they represent, by their content. The content of both perceptual experiences and beliefs is specified by how the world must be for them to represent things correctly; it is specified by stating the conditions under which they would be true.

An introductory course in philosophy begins with Plato's Apology. Here Socrates famously states that ‘the unexamined life is not worth living for man’. The professor lingers on the idea. In this first week of the course they have already struck upon a justification for all of the torturous analyzing, arguing, and thought-experimenting that will follow in the next few months. Without these vehicles of ‘examination’, our lives are not worth living! The students may have experienced enthusiastic defenses of the value of academic disciplines from other professors, but this guy is selling the idea that philosophy is necessary for a meaningful life.

The barn/barn façade thought experiment is familiar to most epistemologists. It is intended to present a counterexample to certain causal theories of knowledge; in it, a father driving through the countryside with his son says, ‘That's a barn’ while pointing to a barn. Unbeknownst to the father, however, a film crew is working in the area, and it has constructed several barn façades. While the father did correctly point to a barn when he made his assertion, he could have just as easily pointed to a barn façade, and so, many hold, he does not know that the structure at which he is pointing is in fact a barn. If this is so, then it follows that true beliefs formed from reliable causal processes (in this case, vision by a competent observer under normal conditions) may still not qualify as knowledge.

Third-party intervention has been the focus of recent debate in self-defense theory. When is it permissible for third-parties to intervene on behalf of an innocent victim facing an unjustified attack or threat? In line with recent self-defense theory, if an attacker is morally responsible for their actions and does not have an acceptable excuse then it is permissible for third-parties to use proportionate violence against them.

Could it be that one morally ought to do something morally bad? Some people think the answer is obviously ‘No’. Indeed, these theorists may say, it is contradictory to suppose that one morally ought to do something morally bad. Others hold that it is not a contradiction but a sad fact of life that one may be morally required to do something morally bad. This latter position is the one I'll be supporting. If it's the right view, it really matters in practical affairs. For example, almost everyone would agree that it's morally bad to kill an innocent fetus. But this does not settle the question of whether one morally ought to have an abortion, if it can be morally required that one do something morally bad.

The Problem of Evil, as it is typically called, is the strongest argument against the existence of a Deity who is at once all-powerful, all-knowing, kind and loving, and whose reach extends everywhere. Simply stated, the existence of such a being is incompatible with the existence of evil and suffering in the world. We know that evil and suffering exist; thus a Deity such as that described above cannot exist.

Sometimes people wonder why we should look at the morality of property at all. Property rights are taken to be legal constructs. Their validity rests, as Hume suggested, on their utility. In this context it makes little sense to focus on the specific provisions of property law and ask about their moral foundation. What has a foundation in morality is the whole system of property itself: laws, distributions, expectations, conventions. And the general usefulness of this arrangement is so large a question, so fraught with uncertainty, that it is almost beyond serious discussion.

Fraser Smith (THINK 16) argues that Plato's argument against democracy as reconstructed by Jonathon Wolff is flawed because in a ‘modern’ democracy the people do not rule, but instead elect officials subject to a system of checks and balances. Smith's conception of democracy is much like Churchill's (and Popper's). I will argue that Smith's reply does not address Wolff and Plato's argument. I will then point out that Aristotle replied to Plato's argument in an appealing – and strikingly modern – fashion. Aristotle, I conclude, did justify to at least some degree democracy, and hence did address Plato's argument.

I here respond to James Warren and John Shand's replies to my paper ‘In Defence of Four Socratic Doctrines’ (all published in THINK 17) by questioning the supremacy of contextualist history of philosophy over the so-called ‘analytic’ approach.

Paul Kurtz's article ‘Morality is natural’ in THINK 15 was most stimulating. It left me, however, somewhat dissatisfied. Whilst he is clearly right that that there is a fund of moral wisdom that has been developed by humankind, I question whether distancing morality from religion is the important priority for us today.