A common `classification' category is `other'. No matter how homogeneous the other categories in use may be, this one seldom is: yet it sometimes gets treated as if it were. Quite frequently, it arises under other names: various mammals with prominent front teeth which didn't fit into any other order are classed as `rodent', despite little else to unify them; the non-indo-european languages of Europe got described as `Finno-Ugric' on grounds of quite tenuous links between them, but the `group' is blatantly just an `other' category (albeit one which might contain some substance). In another common case, one category will be `like the person who devised the classification scheme' and the rest are a decomposition of `other'; the former will stand out by being quite tightly drawn, the rest by being defined mainly in terms of how they differ from it; again, it is rash to assume that these categories are as homogeneous as the `like me' one.
Another great property of `other' is how categories get handled: a motorist will acknowledge that some (implicitly few) motorists are irresponsible - but that's no grounds for restricting the liberty of motorists - while happily agreeing to restrictions on bicyclists which would appear to be justified by the belief that all bicyclists are teenagers with no sense, let alone respect for other road users. What's happening here is that a few (admittedly very noticeable) bad folk in the same category as me are clearly exceptions; but even one bad member of some other category is grounds for the whole of that category to bear the punishment due to that one. Just so did the U.S.A.'s whites persuade themselves (when their police had managed to get one black man convicted of rape) that `blacks are rapists'; yet, when Ollie North smuggled guns from Arabs to terrorists (oops, sorry, that's `freedom fighters' - they were on the U.S.A.'s side, so they can't have been terrorists) and hard drugs from both into the U.S.A., well, that was just a bit of high spirits, you know ? My kind should be forgiven for minor transgressions, your kind `must pay' for what `you' did to `one of ours'.
Written by Eddy.