Why science needs debates

Charles Darwin did not write The Origin of Species (1859) while floating in a cosmic vacuum. Leaving aside the fact that his own grandfather, the physician and visionary Erasmus Darwin, had written the first evolution-oriented book 90 years earlier, French naturalists had also been heating up the subject during the early decades of the 19th century. And the critical point of that latent intellectual revolution was a debate. Yes, a debate, one of those things that politicians with high approval ratings so often drag their feet about. The face-to-face controversy took place in 1830 between Étienne Geoffroy and Georges Cuvier, the two leading French biologists at the time, who were bitter enemies in scientific and other matters.

Geoffroy is the antihero of this story. His critical intelligence had been obsessively focused on the unity that underlies the heady diversity of the living world. A human, a whale and a bat could not be more different from the outside, but it is enough to dig a little into their structure to find the deep logic they share. Inside a whale’s fin are the humerus, ulna, radius, wrists, and five fingers, only reshaped and somewhat wasted. The same can be said of the bat’s wings. There is a fundamental structure, a unity of plan, under the capricious appearances. This was Geoffroy’s mindset, and it obviously prefigures the idea of evolution.

But the debate was won by Cuvier, who was a much more skillful orator. That makes Cuvier the villain of the great 19-century controversy, because the man has been portrayed as a reactionary figure who opposed the flow of history. This portrayal is not accurate. Cuvier preferred to focus on the extraordinary adaptation of living things to their environment and living conditions: the fact that whales had fins and bats had wings, whatever the fundamental architecture of those appendages.

Social media was still two centuries away, but the debate became so well-known in Paris that it immediately reached the ears of Goethe. And of Darwin, of course, a few years later. In fact, the great British naturalist resolved the discrepancy by looking at the matter from a step above, as has often happened in the history of science. The unity of design of humans, bats and whales is explained by their common origin. And adaptations to the environment are explained by natural selection. That is Darwin’s theory. A synthesis, like all scientific advances.

The last great debate started in 1998, when the neuroscientist Christof Koch and the philosopher David Chalmers bet a case of wine, with Koch claiming that it would take no more than 25 years to figure out how the brain generates consciousness. That deadline has arrived, and the annual meeting of the Association for the Scientific Study of Consciousness (ASSC) declared the philosopher to be the winner last Friday at an event in New York. Chalmers says that Koch took a big gamble with the date, but also admits that the field has come a long way in these 25 years, and he no longer has any doubt that researchers will eventually solve that fundamental enigma that has puzzled us for 100,000 years.

Knowledge makes progress through debates. Stop dragging your feet.

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