I shall (stipulatively) define a free action as one a man is able to do. Various things limit a man's freedom. The most unpopular is the government, or other people who have the power of preventing us from doing what we want. But our freedom is also circumscribed by lack of physical and mental strength or skill, including that of knowing how to manage other human beings. Other factors limiting our freedom are our ignorance, our passions and our habits. Some men say they value their freedom from these things, especially their freedom from passion, so much that they would prefer to be in prison or on the rack rather than be a slave to them, but one suspects they exaggerate.

Philosophy unties the knots in our thinking, which we have tangled up in an absurd way; but to do that, it must make movements which are just as complicated as the knots.1 A claim to know can be contradicted in various ways. Which of them does the sceptic have in mind when he denies that we can know—for example, that the sun will rise tomorrow? Does he mean, perhaps, that the proposition is false—that the sun will not rise tomorrow? The sceptic is in no position to make such a claim. Does he mean that no one can feel certain of the proposition? No; the fact that people feel certain of it is not in dispute. The sceptic's argument is essentially about justification. He claims that we do not have the right to feel certain, nor, therefore, to claim to know. But how can he arrive at this conclusion?

In connection with the special theory of relativity, Einstein made use of a now familiar thought experiment1 involving two lightning flashes, a railway train, and an embankment. Whether he used it merely to help explain the theory to others or whether it played a role in the theory's very generation as well is perhaps a matter of conjecture. However, physicist Richard Feynman, for one, believes that Einstein first conceived his theories in the visualizations of thought experiments and developed their mathematical formulations afterwards. According to a recent magazine essay, ‘Einstein came to an understanding about relativity by imagining people going up in elevators and beaming light back and forth between rocket ships.

There is not, and may there never be, any treatise by me …onthese things, for the subject is not communicable in words, as othersciences are. Rather is it that, after long association in the business itself and a shared life, a light is lit in the soul, kindled, as it were, by a leaping flame, and thenceforward feeds itself (Plato).

To forgive a person for a wrong he has done has often been valued as morally good and as indicative of a benevolent and merciful character. But while forgiveness has been recognized as valuable its nature as a moral response has largely been ignored by modern moral philosophers who work outside the confines of a religious context.1 Where it has been discussed, forgiveness has been thought particularly difficult to define, and some have thought the forgiving response paradoxical or even impossible. I shall discuss some of these difficulties and suggest firstly that the value of forgiveness lies in the fact that it essentially requires a recognition of the wrongdoer's responsibility for his action, and secondly that forgiveness typically involves an effort on the part of the one wronged: a conscious attempt to improve oneself in relation to the wrongdoer.

Absolutely no one still believes that every physical interactionconsists of material bodies bumping into each other. Those who have tried to work out a completely mechanistic physics have been unable to explain common phenomena like liquidity, gravitation and magnetism. In fact, there is great reason to doubt that such a physics could ever account for attractive forces in general.