As Williams points out, the motivation behind this search for truth lies "deep in a quite natural conception of enquiry". Descartes, as a "pure enquirer", desires a level of knowledge that is above the ordinary and this is to be achieved through the "method of doubt". .
Descartes first resolves to call the senses into doubt. He argues that "everything that [he] accepted as being most true [he] acquired from or through the senses"; however, he also notes that his senses have occasionally deceived him "and it is prudent never to trust those who have deceived us, even if only once". However, it is questionable whether it is reasonable to wholly reject the testimony of the senses, even if they have sometimes been wrong. Indeed, as Cottingham points out, "is not our very ability to judge that the senses sometimes deceive us parasitic on the fact that they are sometimes non-deceptive". Although our senses might deceive us of the exact shape or size or location of, for example, a table whilst standing in a dark room, or without one's glasses on, or if drunk, once the light is switched on - or glasses found, or one has sobered up - the senses adjust themselves and we become aware of the exact situation of the table. We can recognise that our senses have deceived us and thus correct them. Therefore, critics who argue in this vein conclude, we can be sure that our senses do not deceive us in optimal circumstances (i.e. in bright, natural light). However, this criticism ignores certain issues. In a bright light, when we are able to assess a situation clearly, our senses may still deceive us. For example, the tabletop, although it appears to be perfectly square and flat to the naked eye, might on closer examination prove not to be so: the corners might not be at exact right angles, and it might be discovered that, when viewed through a microscope, the table surface is in fact quite bumpy and not exactly flat.
