The task of thinking is – not always, certainly, but often - to force words out of their customary meanings in order that they might function in new ways and generate new kinds of thought.
And whilst it is true that philosophers need a certain inherited language in order to get thinking started, it is also the case that this inherited language frequently carries with it the assumptions they are trying to analyse, to ‘parse’, to get underneath.
When philosophers begin, for example, to challenge the subject/ object distinction, the very language they use can presuppose what they are attacking. Language can be forced into paradox. This is why what philosophers write can often appear as nonsensical, because the ideas appear to be contradicted by the very language in which they are couched.
Certain terms will be used in scare quotes, metaphorically, in a significantly new yet not arbitrary sense. Philosophical writing will require the reader to 'get' not simply individual words or sentences but the direction of thought, in order for the words to be intelligible. It is like a script written in invisible ink, that will reveal itself only to those reading the text from a certain angle – like the skull in Holbein's Ambassadors. Those reading literally or uncharitably will be lost. Instead, the reader must be on guard, alert to the different directions from which sense, meaning, will approach. This is of course something we do all the time with poetry and fiction. Not that philosophy is like poetry and fiction, but it is, or can be, similarly at a distance from the language we are used to.