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Is a Whale a Fish?

Trying Leviathan: The Nineteenth-Century New York Court Case That Put the Whale on Trial and Challenged the Order of Nature
MD. Graham Burnett. 2008. Princeton University Press, Princeton, New Jersey. 226 pp., hardbound, $29.95.


Is a whale a fish? Of course not. A school-aged child will answer with confidence that a whale is a mammal—and smugly correct the misguided soul who says otherwise. So it’s hard to imagine what a radical taxonomic assertion this was in 1819, when the outcome of a sensational trial in New York City, Maurice v. Judd, hinged on just this question.

Trying Leviathan cover

The New York state legislature had recently enacted a law dictating that fish oil be inspected for quality and purity prior to its sale. Fish oil purveyors had to submit their barrels for inspection—and, of course, pay a fee to the inspector for the privilege. Maurice, New York City’s fish oil inspector, was suing Judd, a seller of whale oil who failed to submit his product for inspection; Maurice wanted to recover his fees and the statutory fines. In his defense, Judd argued that whale oil was not fish oil, so no inspection of his goods or payment of inspection fees was required. Both sides were represented by some of New York’s most high-profile lawyers, and the public followed the case with the avidity of American Idol fans.

In Trying Leviathan, Princeton University science-historian D. Graham Burnett puts this complex case in the social, political, economic, and, particularly, scientific context of the time, about midway between Linnaeus’s 1758 Systema Naturae and Darwin’s 1859 The Origin of Species.

The defense’s star witness was one Samuel Latham Mitchill, an eminent New York natural philosopher who tried to teach his fellow New Yorkers the still-controversial science of Linnaean taxonomy based on classifying species according to their internal anatomical similarities—which make a whale decidedly not a fish. In contrast, according to the taxonomy codified in Genesis, which divided animals into those that swam in the deep, crept on land, and flew in the sky, a whale was obviously a fish. When it called Mitchill, the defense believed his scientific authority would make short work of the plaintiff’s case. Instead, poor Mitchill was literally laughed out of the courtroom and made to look ridiculous in the court of public opinion for years to come.

The plaintiff’s lawyers made much of the fact that Mitchill was happy to admit that there was disagreement even among philosophers about the new classification scheme, reminiscent of creationists who use disputes among evolutionary biologists to suggest that evolutionary theory in general is wrong. They also played on Mitchill’s including man among the primates and by extension making whales more like men than fish. But equally damaging was that a whale not being a fish simply defied common sense.

It’s not that most people who knew anything about whales were ignorant of the features that Mitchill cited as evidence that whales were mammals, such as breathing air and giving birth to live young that were fed with milk. For instance, the whalers called to testify on the question knew that. But, as Burnett explains, those features were simply not salient to how most people classified animal life. Similarly, after science was defeated on the stand, the defense took another taxonomic tack on the case that made much more sense to the jury. They argued and called merchants to testify that, regardless of whether whales were fish, whale oil and fish oil were entirely different commercial products, with different uses and sold at different prices. A customer who ordered fish oil would not expect to receive whale oil and vice versa.

In the end, though, the plaintiff won his case by appealing to regional prejudices: Many of the witnesses for the defense were “easterners” from Boston and such parts, and a jury of New York Knickerbockers proved loath to kowtow to such foreign ways of thinking and speaking. Ultimately, however, the wording of the statute was changed soon after the trial to exclude whale oil from inspection—not because science finally triumphed but thanks to the influence of whale oil merchants whose profits suffered from paying the inspection fees.

Burnett concludes with a thought-provoking discussion of why scientific taxonomy finally prevailed—why everyone now knows that a whale is not a fishand how that might not have been for the best. Fascinating, challenging, rich in historical detail, and sometimes very funny, Trying Leviathan is a whale of tale.

—Susan Lumpkin