The (Anti-)Magnetic Powers of Garlic

Lehoux - RomansA long time ago it was apparently common knowledge that garlic was the kind of thing that, if you rubbed it against a magnet, would rob the magnet of its magnetism.

Today, despite its ability to rob even the most magnetic among us of our powers of attraction (at close quarters), it is common knowledge that garlic has no (anti-)magnetic powers where loadstones are concerned.

How did this radical shift in knowledge come about?

According to Daryn Lehoux, author of the critically acclaimed book What Did the Romans Know? and yesterday’s expert guest at the Situating Science Summer Camp, claims of garlic’s (anti-)magnetic powers have more to do with how we classify garlic than with our experience of garlic’s effects on magnets per se.

Here’s a quote from Lehoux’s book, dating from the seventh century AD and drawn from an ancient Greek text:

“None should be ignorant that it is because of a natural sympathy that the magnetic stone attracts iron to itself, nor that because of antipathy garlic rubbed on the magnet impedes it in its natural action.”

Here’s a modern day quote, said by me about the (anti-)magnetic powers of garlic:

“Everyone knows rubbing garlic on loadstone will not have any effect whatsoever on the magnetic properties of that loadstone.”

I have no special knowledge of the effects of garlic on magnets. Nor do I plan on testing them. Yet, I feel quite confident appealing to experience when denying any link between the two.

In the ancient quote above, Lehoux claims we should expect that the author similarly had no experience of empirical evidence to support his claim of an obvious link between the two; the ancient author probably didn’t run an experiment. Do we really think ancient garlic had such powers? No. Yet we have every reason to believe that the ancient author believed in such a link. In other words, the ancient author, like me, felt no need to actually test the (anti-)magnetic powers of garlic to support the strong claim we make demonstrating our beliefs about those powers.

Lehoux argues that the ancient claims, the current claims, and the shift in between, hinge on how we categorize garlic, as a thing either capable or incapable of having (anti-)magnetic powers. In other words, it used to be the case that garlic was understood as a substance with antipathetic properties where magnetism was concerned, and now it is not. Ancient claims required no evidence, even though they could be clothed in the language of experience. Modern claims are the same. Hence the corresponding claims. No experiment is necessary to make the claims, just an appeal to common knowledge about what sorts of things garlic and magnets are or are not.

This, says Lehoux, is the power of scientific classification. Classification has epistemological and ontological implications for scientific claims. It has the ability to “constrain us as agents directly, by creating, limiting, or determining possibilities for human action and for human moral responsibility.”

Interesting, yes? Want to know more about classification as an epistemic force? Read Lehoux’s book!

Follow the activities of the summer camp at @situscisummerschool.


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