Metaphors are bad for science, except when they transform it

I love cybernetics, a funny body of work from the 50s-70s that attempted to give us a general theory of complex systems in the form of systems of differential equations. I love it so much that it took me years to realize that its metaphors, while offering wonderful links across the disciplines, are just metaphors, and would be incapable of leading me, the young scientist, towards new discoveries. Because in every discipline you find ideas that are just like those offered by cybernetics, except that they are specific, nuanced, grounded in data, and generative of insights. Cybernetics, for me, is a great illustration of how metaphors let science down, even when they are science-y. But there are exceptions.

James Hutton is the father of modern Geology, and in many ways he’s the Darwin of geology, although it might be more fair to say that Darwin is the Hutton of biology, as Hutton preceded Darwin by a generation, and his geology was the solid ground that the biologist’s biology ultimately grew on. Like Darwin, Hutton challenged the tacit dominance of the Bible in his field. The understanding, never properly questioned before him, had always been that the Earth was only a few thousand years old and had formed its mountains and hills and continents over several days of catastrophes. The theory that preceded Hutton is actually termed catastrophism, in contrast to the theory he introduced, that the earth is mind-bogglingly old, and its mountains and hills the result of the drip drip drip of water, sand, and wind.

How did he come up with that? Writer Loren Eisley gives us one theory: Hutton was trained as a physician. His thesis was on the circulatory system: “Inaugural Physico-Medical Dissertation on the Blood and the Circulation of the Microcosm”. Microcosm? That’s in there Hutton subscribed to the antiquated belief that humans were like the Universe in miniature. He observed that the dramatic differences between our young and old are the result of a long timeline of incremental changes, occurring in the tension between the constant growth and death of our skin, hair, nails, and bones. If humans are the result of a drip drip drip, and they are a copy of the universe, then incremental processes must account for other things as well. And there you have it, a shaky metaphor planting the seed for a fundamental transformation not only in how humanity views the earth, but how it views time. Hutton invented deep time by imagining the Earth to be like the body. Eisley called it “Hutton’s secret”: the Earth is an organism, and it’s there underneath us now, alive with change.

So big shaky metaphors can serve science? Really? What if Hutton was a one-off, lucky. Except he’s not alone. Pasteur’s germ theory of disease came out of a metaphor baked deep into his elitism and nationalism: as unlikely as it seems, tiny things can kill big things, the same way the awful teeming masses threaten the greatness of Mother France and her brilliant nobles. So there’s two. And the third is a big one. No grand metaphor has been more important to the last few hundred years of science than “the universe is a clockwork”, especially to physics and astronomy. This silly idea, which had its biggest impact in the 18th and 19th centuries, made thoughts thinkable that most of classical mechanics needs to make any sense at all.

I’m still not sure how bad metaphors lead to big advances. All I can figure is that committing 100% might force a person out of the ruts of received wisdom, and can make them receptive to the hints that other views pass over. Grand, ungrounded, wildly unfounded metaphors have a place in science, and not just any place. We can credit them with at least two of humanity’s most important discoveries from the last 250 years.