  To see why category distinctions were so important to Ryle, we need to look at another major influence: Bertrand Russell. Russell argued that a range of paradoxes (including his famous set-theoretic paradox and the Liar paradox) can be solved by restrictions of type. For example, the famous set-theoretic paradox requires considering sets that are (/ are not) members of themselves. However, if ‘is a member of \(s\)’ is a predicate that can only meaningfully be predicated of objects of a certain type which does not include \(s\) itself, then ‘\(s\) is (/ is not) a member of \(s\)’ is simply a meaningless sentence, and the paradox cannot even be properly expressed. This inspired two related ideas, which gained further support from the work of Wittgenstein and the logical positivists: first, due to some kind of type confusion, apparently grammatical sentences might nevertheless be meaningless; second, apparent philosophical puzzles might be resolved by exposing type confusions and declaring the sentences allegedly stating the puzzle meaningless.