LAWS AS NECESSITIES

Among the things we seek in science are the laws of nature. Various proposals have been made in the history of science as to the laws which govern the events in our world. What have been proposed as laws of nature have generally turned out to be false. But many of them have been, we trust, reasonably near the truth. The actual laws, whatever they are, are somewhat different from the laws which have been proposed. Yet in some sense, these alleged laws resemble the actual laws – or at least some of them are not as far from the truth as others.

Consider some examples. It has been proposed as a law that what goes up must come down. This has been refined in a variety of ways. Greek atomists, such as Lucretius, believed that there was a particular direction (“down”) such that anything composed predominantly of earth or water must always move in that direction unless prevented from doing so by an obstruction. Objects moving in that direction would be moving along parallel lines.

The more astronomically informed Greeks, however, from the Pythagoreans through Aristotle to Ptolemy, believed that the earth was round. Aristotle and Ptolemy believed that earthy or watery things must always move, not in parallel lines, but towards one particular point, the centre of the cosmos, unless prevented from doing so by the presence of an object between them and that point.