I am rereading Berkeley's Three Dialogues between Hylas and Philonous and am curious about any subsequent works which actively rebut his dismissal of primary qualities.
From the first dialogue:
Phil. You are still then of the opinion that extension and figures are inherent in external unthinking substances.
Hyl. I am.
Phil. But what if the same arguments which are brought against secondary qualities will hold proof against these also?
Hyl. Why then I shall be obliged to think they too exist only in the mind.
Phil. Again, have you not acknowledged that no real inherent property of any object can be changed without some change in the thing itself?
Hyl. I have.
Phil. But as we approach to or recede from an object, the visible extension varies, being at one distance ten or a hundred times greater than at another. Does it not therefore follow from this, likewise, that it is not really inherent in the object?
Phil. You may at any time make the experiment by looking with one eye bare and with the other through a microscope.
[Berkeley, Three Dialogues between Hylas and Philonous - excerpted from Modern Philosophy: An Anthology of Primary Sources, pg. 423-4]
In thinking about this, it really does seem like the materialist is backed into a metaphysical corner. While in grad school, it seemed to me that metaphysics was mostly regarded as a "dead category" (or at least an incredibly uninteresting one, except as it related to the history of philosophy), one without any intriguing questions, and that the field was now essentially relegated to the abstract physicists to figure things out. But I'd like to know if there are any serious rebuttals to the above argument or if the attitude is more "idealism is absurd; there's no reason to argue against it".
My own thinking is something along the lines of: If space is conceived of as a three-dimensional area, then an object has an absolute extension within that three-dimensional area, regardless of any observer. So basically, it has an absolute extension in relation to "the universe at large". But I can just hear Philonous saying, "What! Have you any evidence of this three-dimensional space beyond the immediate qualities you perceive?" To which I'd be forced to answer, "Well, no..."
Also, it just seems like a point that Berkeley would be more than happy to grant, because what I call "the universe at large" seems awfully alike to the impartial and perfect perceiver (God). Both would basically be the yard stick by which all other "things" are measured, and so could easily be analogous, it seems like.
Modern materialists seem to take it as self-evident that "secondary qualities" are completely subjective and don't exist outside of the mind (except in whatever esoteric way they are communicated to the senses through a medium, like vibrations in air molecules hitting the ear drum for sound, wavelengths of light interacting with the rods and cones in the eye for color, and so on). But are there any serious texts which rationally and methodically try to pick apart Berkeley's dismissal of primary qualities? Are these generally in support of materialism, or do they tend to embrace some middle ground with dualism?
Elaboration on "the universe" being analogous to "God": What I mean is that, for Berkeley, "things" (in so far as they can even be called "things") have an absolute extension by virtue of being perfectly perceived at all times by God. I think he would say that this is essentially the same as using the entirety of space as some general and perfect reference point to which all objects are compared and by which they are all measured.