Almost everybody has a conscience, though it may not play a dominating or even very prominent role in his life. To have a conscience is to classify some kinds of action as morally right and others as morally wrong, and to be disposed to do the former and avoid doing the latter. To judge an action as morally right or wrong is not to judge it as advantageous or disadvantageous to the agent; the motive for acting conscientiously cannot be pure self-interest. It is a mark of my thinking an action morally right that I am disposed to do it even though doing it will involve me in a net loss of enjoyment or a net surplus of suffering. A man who is only disposed to do such things as he thinks will increase his happiness in the long run has no conscience. (I do not include among these people those who think that it will be to their ultimate advantage to do what their consciences tell them would be right apart from considerations of ultimate advantage.) Conscience presents itself to a person as a kind of constraint which he cannot evade on the ground that it will be inconvenient to comply with it.

Are there circumstances in which we would be justified in taking one person's life for the sake of others? I am not here concerned with cases of self-defence, or what we might call ‘other-defence’, where one person has to be killed to prevent him taking the lives of others. Nor am I concerned with cases of self-sacrifice, or suicide more generally, or euthanasia; nor with capital punishment, or killing in warfare; nor even, for reasons we shall explore, with abortion. I am concerned with those cases where several people have an equal claim or right to life, the same claim or right which we typically accord to all human beings, but where not all can survive. In short we are faced with a choice, as to who shall live and who shall die.

In recent years philosophers have given much attention to the ‘ontological problem’ of events. Donald Davidson puts the matter thus: ‘the assumption, ontological and metaphysical, that there are events is one without which we cannot make sense of much of our common talk; or so, at any rate, I have been arguing. I do not know of any better, or further, way of showing what there is’. It might be thought bizarre to assign to philosophers the task of ‘showing what there is’. They have not distinguished themselves by the discovery of new elements, new species or new continents, nor even of new categories, although there has often been more dreamt of in their philosophies than can be found in heaven or earth. It might appear even stranger to think that one can show what there actually is by arguing that the existence of something needs to be assumed in order for certain sentences to make sense. More than anything, the sober reader will doubtlessly be amazed that we need to assume, after lengthy argument, ‘that there are events’.

One of the greatest of Hume's philosophical achievements, which becomes in its turn an assumption presupposed by some of the others, is perhaps best stated at the end of the First Enquiry: ‘If we reason a priori, anything may appear able to produce anything. The falling of a pebble may, for aught we know, extinguish the sun; or the wish of a man control the planets in their orbits. It is only experience, which teaches us the nature and bounds of cause and effect, and enables us to infer the existence of one object from that of another’ (XII (iii) 164).

In recent years, much uncertainty and outright scepticism surrounds the notion of character. In the arts—painting, the novel, drama, film—the notion of character has receded into the background. The loss of character is especially conspicuous in those artistic forms in which it traditionally occupied centre-stage: drama, the novel, films. The withdrawal of character from the arts has in fact become a topic of debate in the theory and criticism of the arts. In the arts themselves, the difficulty, if not the impossibility, of attaining character is a common subject. Since ordinary sentiments are readily reflected in the fine arts, it is natural to suspect that character is not held in high regard in everyday life. Even if we take a dim view of the suggestion that the arts mirror ordinary sentiments with little distortion, a decline in the importance of character is evident in other humane disciplines: history is a striking example. Indeed, if we attend to our major social institutions—the family, the courts, the bureaucracy—it would be difficult to point to any in which the question of character is more than a peripheral concern. Indeed, it appears that the appraisal of character is of central concern in modern society only when the individual is in some way beyond the pale: in institutions of punishment, rehabilitation, mental health.

For extravagant young Fellows, that have Liveliness and Spirit, come sometimes to be set right, and so make Able and Great Men: but Dejected Minds, timorous and tame, and Low Spirits, are hardly ever to be raised, and very seldom attain to any thing. To avoid the Danger, that is on either hand, is the great Art; and he that has found a way, how to keep up a Child's Spirit, easy, active and free; and yet, at the same time, to restrain him from many things he has a Mind to, and to draw him to things that are uneasy to him; he, I say, that knows how to reconcile these seeming Contradictions, has, in my Opinion, got the true Secret of Education.