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.

  • Don't you see that non of this contradicts anything? This different views are like operational systems. It is like asking does OS X contradicts Windows? Or is there any OS between OS X and Windows? Meaningless. First you have to (like Descartes) ask yourself if there is anything outside of minD? And then try to fix Berkeley. Otherwise you are talking about THINGS you don't know and it is a sin for materialist :)
    – Asphir Dom
    Commented Apr 22, 2014 at 14:30
  • @AsphirDom That's kind of my point. :) I'm not convinced that there IS any good way to contradict it. That's why I'm asking if anyone has seriously tried and where I can find those arguments.
    – asteri
    Commented Apr 22, 2014 at 14:41
  • You might like Four Dimensionalism, which extends your argument to objects having temporal parts as well as space parts. I would also suggest looking at Lorentz transformation: how I am moving with respect to what I observe affects what I see. So it seems that we need some 'representation' of an object such that individual observations of an object can be "translated" into some objective definition. But can such an objective, observer-independent definition be found?
    – labreuer
    Commented Apr 22, 2014 at 16:04

1 Answer 1


Great question: I think Kant may do so, he takes a mid-point between Berkeleys pure idealism - all mind, and the materialists - all matter. Qualia for him come from the interaction of mind on matter.

It was Humes pure scepticism about causality that awoke Kant from his 'dogmatic slumber'; and the same critique that Hume makes about causality, seems to have a family reemblence with the scepticism that Berkeley makes about space, judging from the extract.

The primary qualia, of space and time are the very conditions of experience, which is why he posits them as synthetic and a priori - a priori because they come before any possible experience; and synthetic - because one can't deduce its existence simply by logical means. If one is given a theory of space, one can't deduce the immediate sensation or qualia of space.

His theory allows for the empirical investigation of extension (in the sense that Spinoza means) and causality, so this means physics is possible, so one can argue that even if, for example, a brick looks such and such a size to me, and it looks like such and such a size to you, there is in fact a conventional sense in which we can say that it has a certain size.

Because Kant allows for physics, we can say that in a certain sense spacetime is a 4-dimensional manifold, even though in our direct experience, space and time are very different phenomena.

He also has a systematic account of Aristotles categories which he places on a foundation via his philosophy.

Your remark about 'the universe at large' being awfully like God is interesting. It was Spinoza that theorised that the material universe (as pure extension) and mind (as pure thought), were two attributes of the single, indivisible, immovable and neccessary substance called God; and Newtons description of space and time has a qualitative, at least to me, link with that idea. I'd be interested to know if that could be drawn out further.

This letter to Nature, for example, shows a possible sphere of influence from Spinoza to Newton, and also Berkeley remarks in his adventure of Ideas:

Also in his general scholium, Newton definitely connects the Lucretian Void with the Leibnizian God. For he calls empty space 'the sensorium of God'.

as for Philonous scepticism of general metaphysics, Whitehead has this to say:

Our metaphysical knowledge is slight, superficial, incomplete. Thus errors creep in. But, such as it is, metaphysical understanding guides imagintion justifies purpose Apart from metaphysical speculation there can be no civilisation.

  • Interesting. Good point about a priori knowledge as a rebuttal. I'll have to go back and read some Kant, though I've only read his Foundations of the Metaphysics of Morals. Would you suggest any other texts?
    – asteri
    Commented Apr 22, 2014 at 13:25
  • Also, I guess I didn't really explain the analogy between the universe and God very well (probably because it's not fully formed in my head). 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.
    – asteri
    Commented Apr 22, 2014 at 13:27
  • well, you've read more of his work than I have :) - physically speaking, this is roughly what the metric on the spacetime manifold does; before applying the metric one has only the notion of contiguity; after application of the metric one can measure, and measure absolutely. Commented Apr 22, 2014 at 13:35
  • You're reading of Berkeley viz God aligns with what little I know of Berkeleys ideas on this - but I'd suggest that there still remains a distinction between God & space in the way that you described, but one can see that there is a kind of resemblence there. The first is theological, the second atheological. One might move from the first to the second by an application of Occams Razor; but I'd suggest that though this is possible in a post-theological philosophy, it mischaracterises how Berkeley (& Spinoza who was thinking along the same but different lines) thought about this themelves. Commented Apr 22, 2014 at 13:38
  • Makes sense. Thanks for your comments. I thought about formatting the idea as a 4-dimensional space-time, but I thought that would muddy the argument without adding any real value. I'm fascinated by theoretical physics, but unfortunately the pure mathematics are far too complex for me. Still, things like the double-slit experiment make the physical world seem magical all over again -- and isn't it interesting and maybe relevant that an observer has such an effect on the universe! :) (As a side note, I read your profile, and your writing is beautiful.)
    – asteri
    Commented Apr 22, 2014 at 13:43

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