I'm still confused.
Assume that a strong wind blows through the trees. My friend and I both perceive this via sight, sound, and bodily contact and thus we can differentiate it as being rupa (although what we are actually perceiving is nama). It would be reasonable to say that we are unable to perceive Rupa (or the behavior itself) directly, rather we are limited to its signs (sight, sound, and touch). What I don't understand is how we can jump to the conclusion that, because we cannot perceive it, it must therefore not exist. It would seem that it does indeed exist, for while my subjective experience of the sight, sound, and feeling of that wind event may be limited to my own perception, we cannot deny that a wind has indeed just blown through the trees. Further, since both my friend and myself perceived this behavior, however indirectly, is it not, in some sense, objective?