that no one knows anything. The theory is self-contradictory. It professes to be skeptical about everything, but, as a matter of fact, it is not at all skeptical of its own skepticism. It has no doubt that everything is doubtful. This position is manifestly untenable. For if we accept the skeptical conclusion, we have to be unskeptical to do so. Or if we are skeptical even about skepticism, we cannot be skeptical. In other words, to be skeptical a person must not be skeptical. A theoretical house