[claudiawerner]

>I imagined he was talking about words like "socialism" or "equality" -- words that are obviously slippery.

Even if this were necessarily true, it wouldn't make philosophizing about them useless; for instance, as slippery as the term 'equality' may be, it's also clear (except for 18th century French philosopher Babeuf) that it doesn't literally mean that everyone in society is allocated and has access to an equal amount of resources.

In my own experience talking about these concepts, much greater confusion and misunderstanding comes from simply not reading the source material, rather than the words having potentially different meanings. Most people (including some socialists) talk about socialism without having read just what its foremost proponents (and critics of their own socialism) have to say.