In his 1958 paper describing what would become Lisp, literally the first example of the use of car he gives is destructively modifying a cons, ie, RPLACA. In his own words, which I quoted earlier and you didn't respond to: "Compared to the mathematically elegant recursive function definition features, the ``program feature'' looks like a hasty afterthought. This is not quite correct; the idea of having sequential programs in LISP antedates that of having recursive function definition."
It seems black and white to me.
> > but what you and Paul Graham seem to be doing is saying that that pure Lisp is the real Lisp and what was called Lisp before that (in theory and implementation)
> This is not my intention.
Could you explain how your intention differs? McCarthy's original conception of Lisp was not purely functional (according to McCarthy himself as well as the historical evidence), and the original implementation was not purely functional, so how would the purely functional subset described in a later paper be "the original LISP" if you aren't denying the earlier work?