For many, science is the central achievement of the twentieth century, displacing the arts as the primary expression of mankind's creativity. As a result, we tend to believe science's myths, notably those about its essential unity. We are told that science proceeds by consensus, and as a result offers a uniquely integrated and unified domain. But this view, written by the mental victors, conveniently ignores the fact that there are really three sciences, not one.
The first is what we normally mean by the term, and what might be more exactly called universal science, if only because of its pretensions. It is Big Science, embracing the crowd-pleaser theories of relativity, quantum mechanics, and cosmology; it is the root of all our treasured modern technologies - computers, non-invasive surgery, space travel; it is the defining cultural influence of our epoch, and informs not just the rhythms of our daily lives, but our whole world-view.
Universal science is a construct of the last three or four hundred years. It supplanted two earlier kinds of science, one a historical relict, now rightly defunct, the other a tradition which endures. The former was based on Aristotelian physics, and represented the sclerotic legacy of the Middle Age's Scholasticism. The latter is often called folk science, but is more truly parochial.
It embodies the tribe's knowledge about the larger forces in life - the weather, the tides, the movement of animals. Today its quaint vaguenesses have been largely superseded by the apparent certainties of its brash younger sibling, universal science. But it persists in those areas, notably the weather, where modern science flounders hopelessly when confronted by a system whose complexity defies simplistic analysis. Lore such as 'red sky at night, shepherd's delight, red sky in the morning, shepherd's warning' clearly proclaims its pastoral origins; it also offers an empirical truth still beyond modern science's ken.
The last of the trinity of sciences might be called personal. It is the solipsistic knowledge that we all have about ourselves, but which has no claim to validity beyond that arena. This science embraces our specialist cures for colds, requirements for a sound night's sleep, ways to avoid hangovers, and combinations of foods and circumstances that are guaranteed to give us indigestion. Just as parochial science is almost exclusively concerned with the local external world, so personal science is about our body, that most intimate internal space.
The progression from personal to parochial to universal therefore represents a constant expansion of knowledge's ambition, from the body, to the village, to all creation. It thus also tracks science's historical rise to power, and its claim to increasing sovereignty. The reverse movement from universal to personal also defines science's limitations. Its theories of sub-nuclear matter and galactic cosmogony are so deep and abstract as to be scarcely refutable; but its feeble and flawed explanation of the weather is a constant reproach; and its ignorance about our purely subjective body-knowledge is near-total.