Descartes' immortal conclusion cogito ergo sum was recently...

Descartes' immortal conclusion cogito ergo sum was recently subjected to destruction testing by a group of graduate researchers at Princeton led by Professors Montjuic and Lauterbrunnen, and now reads, in the Shorter Harvard Orthodoxy: (a) I think, therefore I am; or (b) Perhaps I thought, therefore I was; but (c) These days, I tend to leave that side of things to my wife.