A nonapple is an object, tool, technique, or theory which is defined only as being not like a specific example of said categories. It is a type of overly-general prescription which, while of little utility, can *seem* useful. It involves disguising a shallow criticism as a recommendation, often in such a way as to make it seem profound. For instance, suppose someone says, "We don't need war, what we need is non-violent conflict resolution." Such a person is selling nonapples because "non-violent conflict resolution" isn't a method or resolving conflict nonviolently. Rather, it is a description of all possible methods of non-violent conflict resolution, the vast majority of which are incoherent or ineffective.
The set "apples" is much narrower than the set "not apples". Apples form a compact cluster in thingspace, but nonapples vary much more widely in price, and size, and use. When you say to build a wagon using "wood", you're giving much more concrete advice than when you say "not wood". There are different kinds of wood, of course - but even so, when you say "wood", you've narrowed down the range of possible building materials a whole lot more than when you say "not wood".
- A Human's Guide to Words (sequence)