The greatest idea that's disappeared from mainstream science this past 400 years is surely that of God. The greats who laid the foundations of modern science in the 17th century (Galileo, Newton, Leibnitz, Descartes) and the significant-but-not-quite-so-greats (Robert Boyle, John Ray, etc.) were theologians as much as they were scientists and philosophers. They wanted to know how things are, of course — but also what God had in mind when he made them this way. They took it for granted, or contrived to prove to their own satisfaction, that unless there is a God, omniscient and mindful, then there could be no Universe at all.
Although David Hume did much to erode such argument, it persisted well into the 19th century. Recently I have been intrigued to find James Hutton — who, as one of the founders of modern geology, is one of the boldest and most imaginative of all scientists — earnestly wondering in a late 18th century essay what God could possibly have intended when he made volcanoes. The notion that there could be no complex and adapted beings at all without a God to create them, was effectively the default position in orthodox biology until (as Dan Dennett has so succinctly explained) Charles Darwin showed how natural selection could produce complexity out of simplicity, and adaptation out of mere juxtaposition. Today, very obviously, no Hutton-style musing would find its way into a refereed journal. In Nature, God features only as the subject of (generally rather feeble) sociological and sometimes evolutionary speculation.
Religion obviously flourishes still, but are religion and science now condemned to mortal conflict? Fundamentalist-atheists would have it so, but I think not. The greatest ideas in philosophy and science never really go away, even if they do change their form or go out of fashion, but they do take a very long time to unfold. For at least 300 years — from the 16th to the 19th centuries — emergent science and post- medieval theology were deliberately intertwined, in many ingenious ways. Through the past 150, they have been just as assiduously disentangled. But the game is far from over. Cosmologists and metaphysicians continue to eye and circle each other. Epistemology — how we know what's true — is of equal interest to scientists and theologians, and each would be foolish to suppose that the other has nothing to offer. How distant is the religious notion of revelation from Dirac's — or Keats's? — perception of truth as beauty? Most intriguingly of all, serious theologians are now discussing the role of religion in shaping emotional response while modern aficionados of artificial intelligence acknowledge (as Hume did) that emotion is an essential component of thought itself. Lastly, the ethics of science and technology — how we should use our new-found power — are the key discussions of our age and it is destructive to write religion out of the act, even if the priests, rabbis and mullahs who so far have been invited to take part have often proved disappointing.
I don't share the modern enthusiasm for over-extended life but I would like to see how the dialogue unfolds in the centuries to come.
COLIN TUDGE is a Research Fellow at the Centre for Philosophy, London School of Economics. His two latest books are The Variety of Life and In Mendel's Footnotes.