It has long been pointed out by opponents of skepticism that such an attitude cannot be taken to its extreme conclusion in the real world in which we operate- even skeptics must live their lives according to rules they must rely upon not to fail. Skepticism (and all philosophy) cannot avoid the cumbersome nature of human language and the simple fact that the only tool humans have to investigate the nature of existence is the brain, which spawns coherent thoughts in a lingual form. In day to day life, realistically, the observations and calculations of the brain must be relied upon to reach trustworthy conclusions. The ardent skeptic will certainly not step off of a cliff unless he has a death wish. Obviously anyone who disregarded the law of gravity would be called insane. Therefore, it seems reasonable to accept the reliability of the laws of science. When arguing for his skeptical position, the skeptic would be forced to call into question the reliability of these laws in his refutation of absolute truth, attainable knowledge, etc. This is an apparently irrational behavior by the skeptic- to live by laws that he will later claim unknowable or altogether false. If one chooses to ignore this obvious fact, there is little that can be done to argue, for argument assumes that rational thought processes are at work. As Hank Hanegraaff has said, "Even those who deny reality look both ways before they cross the street."
One popular example skeptics use to disprove attainable knowledge is the Brain in the Vat argument. "The Brain in the Vat scenario is a thought experiment designed to show the plausibility of radical skepticism. If we were merely Brains in Vats, hooked to computers which send the same sorts of