Ever since the Matrix hit the theaters, the old hobgoblin of Solipsism has made a rather tiresome comeback, with dozens of Keanu Reaves fans mumbling about how all our senses can be wrong and we can't be sure of anything but our own minds. "whoah."
Too many philosophers and theologians have fallen to this conclusion, never once asking themselves a very obvious question: what makes you think you can trust your own mind?
The senses can be fooled, yes, but when they do it's an honest mistake. It can be usually be corrected easily with the use of some sense-enhancing instrument like a telescope, hearing aid, or electron microscope. Contrary to some claims, the advancement of knowledge that humanity has gained since the Renaissance has come not by the refutation of our senses but by the enhancement of them. It wasn't a solipsistic argument that determined that the earth was round, it was some guy noting how the horizon of the ocean curved, and how the shadow cast on the moon was similarly curved.
By comparison, the mind can not only be fooled, but it fools itself on a regular basis. Several psychological studies have shown to us how our memory constantly rewrites itself in light of current events, rather like the Ministry of Truth in 1984. The common assumption that your first assumption is usually correct has been statistically proven to be wrong-- it's just that your mind conveniently forgets whenever the first assumption wasn't correct, leaving you with the impression that your first guess is the good one.
This is, of course, nothing new-- Hume pointed out that our impression that our memories are reliable is based only on our own memories-- therefore, our memories can be uniformly flawed and we'd only be aware of it, if at all, by outside clues. And, like all big ideas, even Hume's idea was derived off the thinking of his predecessors.
Anyway, if the senses are fallible, the mind is at least as fallible, possibly moreso. What's more, errors of the mind are harder to demolish than errors of the senses. It only took a few glances through a telescope to destroy the "sensual" conviction that the sun spins around the earth. By contrast, elaborate subjective systems hold together even when all evidence demonstrates their uselessness-- horoscopes, superstitions and that belief that only 5& of the mind is used are widespread despite the fact that they have no reasonable or sensible leg to stand on. It's as if the faculties of one's mind have an arrogance and stubborness of their own, and maintain themselves against evidence that would demolish any belief based on sensual information.
All this, of course, assumes the dubious separation of one's mind and senses, a distinction which is possibly much less easy to draw than many would think.