The Science of Judging a Book by its Cover

Brent Arehart // There is a famous anecdote about Hippocrates told by Arabic authors. One day, Hippocrates’ students gathered to discuss whether anyone else was more virtuous than their master. When they could not think of any obvious candidates, one student got a clever idea. He proposed that they acquire a picture of Hippocrates and put it before Polemon, the famous physiognomist who touted an ability to infer any person’s character from their appearance. When Polemon looked at the picture, he proclaimed his diagnosis: “The man here loves fornication.” Shocked, the students called Polemon a liar and pointed out that this man in question was none other than the great Hippocrates. Polemon refused to recant, daring them instead to go ask Hippocrates himself. But when they asked their master about this incident, he ended up agreeing with Polemon. “I love fornication,” Hippocrates admitted, “but I control myself.”

Setting aside the chronological inconsistencies (Polemon lived centuries after Hippocrates) and onomatological confusion (Socrates sounds like Hippocrates in Arabic script), this charming anecdote illustrates the once familiar relationship between physiognomy and medicine [1]. For those who have never heard of it, physiognomy is the systematic practice of using a person’s physical features to ascertain their character traits. (In other words, physiognomy purports to be the science of judging a book by its cover.) Whereas today medicine is generally accepted as a scientific practice, physiognomy sounds more like phrenology—a pseudo-science that pretends to make meaningful mountains out of superficial molehills. But from a historical perspective, medicine and physiognomy have more in common than it may seem at first.

Unsurprisingly, scholars disagree over the extent to which physiognomy and medicine overlapped in antiquity. The fact that both rely on the interpretation of signs to arrive at a “diagnosis” seems like dubious grounds for totalizing one into the other—not to mention the fact that medicine used diagnoses for the sake of treatment whereas physiognomy used them for the sake of judgement. Yet, theoretically speaking, the two are not always so easy to differentiate. Take the opening lines of Pseudo-Aristotle’s Physiognomics for example:

That minds follow their bodies and are not isolated and unaffected by the changes of the body is something that becomes very clear in cases of drunkenness and illness. For, states of mind appear to change a great deal through the affections of the body. And correlatively, the body is clearly affected along with the affections of the soul in cases of love, fear, grief, and pleasure. (1.1, trans. Swain, slightly modified)  

It is hard to disagree with Pseudo-Aristotle here. Everyone who has been drunk or ill at some point knows that the mind is affected along with the body. We would all even agree that certain signs (slurred speech, vomiting, irascibility) can indicate that a person is drunk or ill without the need for corroboration from the person themself. So, signs of illness were just one of many medical analogies that Pseudo-Aristotle could draw on to make his case that physiognomy operates like a science.

 At the same time, there were limits to what the physiognomist could discern, as Pseudo-Aristotle was aware:

Permanent bodily signs will indicate permanent mental qualities, but what about those that come and go? [. . .] There are affections of the soul whose occurrence produces no change in the bodily marks [ . . .]; you cannot recognize a doctor or a musician, for the fact of having acquired a piece of knowledge will not have produced any alteration in the bodily signs on which the physiognomist relies. (1.1, trans. Swain, slightly modified)

Not everything a person does produces a detectable sign. Thus, where there are no signs, there is no physiognomy. A doctor could use the same logic: if there are no signs of a particular illness, then there is nothing to prove the presence of that illness. But if medicine and physiognomy were similar in theory, could we not just tell the two apart by their practitioners? The answer, however, would be no. For essentially all of antiquity, a doctor was whoever claimed to be a doctor. Sure, someone like Galen would emphatically deny that that was the case, but if Galen had it his way, only he and a handful of intellectuals from the time of Hippocrates to his own day would count as “real” doctors (i.e. the No True Scotsman fallacy). So, while Pseudo-Aristotle would argue on principle that you will not simply recognize a doctor when you see one, Galen’s own rhetoric would often suggest that you will know a doctor when you see one. (Hint: they resemble Galen, of course!)  

In some respects, it seems unremarkable that medicine and physiognomy would both privilege appearance as a valuable diagnostic tool. When you see blood in someone’s urine, there is a good chance that something has gone amiss. But there are subtler examples of the shared intellectual milieu between the two. In his work The Art of Medicine, for instance, Galen claims that people with a moist, cold heart are cowardly and fearful (11, I.336 K). People with a larger chest are the least prone to anger (11, I.336 K). People with a hot, moist liver are less hairy on their abdomens (12, I.228 K). And men with warm testicles are more fertile and likely to produce male offspring (13, I.339 K). Galen could cite various aspects of humoral theory, or appeal to the hot, the cold, the wet, and the dry to back up his assertions. Then again, so could a physiognomist, and both would be correct for the same reasons.   

When approached at the abstract level, medicine and physiognomy are both forms of reasoning that seek to explain observations. Even at the empirical level, both are concerned with drawing conclusions about the physical body. I do not mean to suggest that there is no difference between medicine and physiognomy (I would never entrust my health to a practitioner of the latter!), but only that when we look back on the history of medicine, the devil really is in the details.   


1. Following the anecdote as it is found in Ibn Juljul’s Ṭabaqāt al-aṭibbā’ and translated in Franz Rosenthal, The Classical Heritage in Islam (New York: Routledge, 1975 [repr. 1992]): 254. A Google preview can be found here. In Classical Arabic, Hippocrates is often called Buqrāṭ or Buqrāṭīs.

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