The Blank Slate: The Modern Denial of Human Nature

by Steven Pinker

A slippery slope assumes that conceptual categories must have crisp boundaries that allow in-or-out decisions, or else anything goes. But that is not how human concepts work. As we have seen, many everyday concepts have fuzzy boundaries, and the mind distinguishes between a fuzzy boundary and no boundary at all. “Adult” and “child” are fuzzy categories, which is why we could raise the drinking age to twenty-one or lower the voting age to eighteen. But that did not put us on a slippery slope in which we eventually raised the drinking age to fifty or lowered the voting age to five. Those policies really would violate our concepts of “child” and “adult,” fuzzy though their boundaries may be. In the same way, we can bring our concepts of life and mind into register with biological reality without necessarily slipping down a slope.