Therefore he was.(Descartes)(Book review)

Descartes, by A.C. Grayling; Free Press, 2005, $39.95.

DESCARTES LED A QUIET, scholarly life, but there are some things which seem out of character. For example, though he was always a devout Catholic, he joined the army of Prince Maurice of Nassau, which was a Protestant army. Moreover, he went, by a curiously circuitous route, to witness the battle of White Mountain in Bohemia, which began the Thirty Years War. And, though a great letter writer (there are eight volumes of correspondence) he was secretive about his address.

A.C. Grayling puts forward the suggestion that Descartes doubled as a Jesuit spy, though spy is not exactly the right word--intelligence gatherer would be better. About a generation later in England, the philosopher John Locke worked as secretary to the Earl of Shaftesbury, who ran the secret police in the reign of Charles the Second. So undercover operations were not unknown to great philosophers.

Descartes lived most of his adult life in Holland. There is no doubt that he appreciated the liberal atmosphere, free from dangerous enquiries of the kind that tormented Galileo. And perhaps there was something else. Grayling suggests that Descartes may have been part of the Jesuit network which supported the Habsburg cause in the Thirty Years War, and that high French officials, notably Cardinal Berulle, may have got wind of that, and since that would have been counter to French opposition to the Habsburgs, they advised him to leave France.

In Holland, Descartes' liaison with a chambermaid resulted in a baby. Though Descartes did not marry the mother, he did not repudiate her, and loved the child, a girl, Francine--who died when she was six years old, to Descartes' grief.

Holland was the scene of Descartes' intellectual labours. It was there that he invented the geometry which bears his name, and puts him in the company of the great mathematicians. It was there that he constructed his famous philosophy, beginning with "I think, therefore I am." His philosophy has the effect of bifurcating nature into the mental and the physical, the former being the province of thoughts, hopes, feelings, desires, intentions, ambitions, dreams, and all that we are aware of from within.

Matter was defined by "extension" which means being spread out in space. Extension is wholly lacking to mind which is defined by thought (and so on). That produces odd consequences for Descartes. The mind, or thinking self, is capable of surviving death, but it could not have a face, since that would be extended and hence material. How might people be recognised without faces?