Steven Shapin on William Petty

I first remember hearing about William Petty (1623-87) in a class on advanced cartographic design offered by David DiBiase at Penn State as a grad student. Petty’s “fever line” charts (line graphs) of the national debt were innovative and “spoke to the eyes” as he wrote. They were an act of visual rhetoric designed to convince people of his opposition to debt: a new field of “political arithmetic.” Today of course no self-respecting economist (or grad student) is without a handy line chart or two.

What I didn’t know was that Petty was a cartographer as well as a “mathematician, mechanic, physician…and statistician.” The words are those of the historian of science, Steven Shapin in the Jan 20 London Review of Books. Why cartographer? Shapin:

Arriving in Ireland in 1652 as physician-general to the army, he set about making himself useful to the Cromwellian forces. He started with the reform of military medicine, but the project on which he soon set his stamp was the mapping of land, surveying the boundaries of holdings and assessing relative values. This became known as the Down Survey, which McCormick plausibly describes as the first imperial survey of a land conquered by Britain and the ‘greatest single state-supported scientific project of its day’. The term of art for the type of representations Petty helped produce is a cadastral map: cadastral data concern the boundaries of property and information about its value.

This survey of course was hardly innocent but part of the “replanting” (strange phrase) of Ireland in the sense of populating it with English Protestants in 1652: an “ethnic cleansing” (Shapin).

If this was news to me then not to Shapin who manages to get off a trendy zinger about Foucault:

Cadastral mapping in general, and Petty’s Irish survey in particular, have been worked over before by scholars concerned with the practices of modern state-making – notably by Mary Poovey, Patrick Carroll and any number of Foucault-followers writing about ‘governmentality’.

Shapin argues that the book he’s reviewing (McCormick’s William Petty and the Ambitions of Politicsal Arithmetic) does something “substantially new” to the Foucault-heads:

The state needed to know what Ireland was and what it had. It needed to know, and to know with accuracy, how land was parcelled out, how it should be classified according to its natural history, geology and productive uses, whether it was ‘profitable’ (‘arable, meadow and pasture’) or ‘unprofitable’ (‘wood, bog and mountains’).

In sum,

the language of practical statecraft. How to describe the wealth of a nation; how to know what human activities were the bases of that wealth; how to manage the practical transformations between land, labour and money? How, in general, to make a state and its inventories legible in the language of number? And how to use that legibility to govern?

Shapin is correct, though he obviously doesn’t recognise that these are exactly the questions “Foucault-followers” are attempting to address in studies of governmentality. This paragraph could almost be lifted from Foucault’s famous lecture of 1 February 1978.

Petty was a man well ahead of his time in this regard. We don’t usually accredit the growth of cartographic involvement in “state-istics” until the late 18th C, a hundred years later. Yet Petty is obviously not an isolated case, or a man without impact. Any history of cartography and government would have to include him alongside the history of Napoleon in Egypt and the Cassini’s. The statistical atlases of the 19th C. are “Pettian.” I look forward to reading McCormick’s book, which is apparently and amazingly the first biography of Petty.


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