[mannykannot]

The view stated in your last sentence is a commonly-held one, but if we needed complete definitions of something before we could have knowledge of it, I doubt we would ever have come up with the idea of a gravitational field or a wave function. The solid definition of consciousness will follow from our future understanding of how minds work, not be a prerequisite for it.

[seiferteric]

> I doubt we would ever have come up with the idea of a gravitational field or a wave function.

But that is the opposite of the case here. We came up with those ideas after we had an understanding of the system. With consciousness, people casually use the term all the time and think they have a vague idea of what it is, but we have little understanding of the system. It may be that it simply does not exist for example.

[mannykannot]

you have a point - they are not exact analogies - but, as you say, we came up with those ideas after we had an understanding of the system. If we can discover things without having a prior definition of them, then having a vague prior definition should be no obstacle - even if it leads to some initial confusion, clearing that up through the gathering of evidence should be no harder than coming up with a definition for something we previously did not suspect through the gathering of evidence.

This is so even if it turns out that the phenomenon does not exist, such as in the case of the mythical causal effects of the four humors.