In chapter two of In Praise of Prejudice, Dalrymple observes that unlike Rene Descartes, the 17th century philosopher who systematically subjected everything to doubt in order to see if there was anything of which he could be absolutely certain, modern Cartesians wish to destroy certainty itself.
The popularity of the Cartesian method is not the consequence of a desire to remove metaphysical doubt, and find certainty, but precisely the opposite: to cast doubt on everything, and thereby increase the scope of personal license, by destroying in advance any philosophical basis for the limitation of our own appetites. The radical skeptic, nowadays at least, is in search not so much of truth, as of liberty—that is to say, of liberty conceived of the largest field imaginable for the satisfaction of his whims. He is in the realm of moral conceptions what the man who refuses to marry is in the realm of relationships: he is reluctant to foreclose on any possibilities by imposing limits on himself…
The skepticism of radical skeptics who demand a Cartesian point from which to examine any question, at least any question that has some bearing on the way they ought to conduct themselves, varies according to subject matter. Very few are so skeptical that they doubt that the sun will rise tomorrow, even though they might have difficulty offering evidence for the heliocentric (or any other) theory of the solar system. These skeptics believe that then they turn the light switch, the light will come one, even though their grasp of the theory of electricity might not be strong. A ferocious and insatiable spirit of inquiry overtakes them, however, the moment they perceive that their interest are at stake—their interests here being their freedom, or license, to act upon their whims. Then all the resources of philosophy are available to them in a flash, and are used to undermine the moral authority of custom, law, and the wisdom of the ages. (pp. 6-7)