I'd like to know how the following argument by George Berkeley can be challenged:

(1) If primary qualities cannot be abstracted from secondary qualities, then primary qualities cannot exist apart from secondary qualities.

(2) Primary qualities cannot be abstracted from secondary qualities.

(3) Secondary qualities are nothing but sensations or ideas that exist only in the mind.

Conclusion: Primary qualities exist only in the mind.

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    (1) is ambiguous: if primary qualities are already separate, then they might not be abstractable from secondary ones, but this would nullify the consequent. (2) might be denied straightaway (as by saying that material subsistence is extension, a la Descartes). But even (3) is not as horrible as it might seem: Berkeley grants that God's mind is good enough to hold the world fast when no one else is looking, and we might even take our own minds to unconsciously represent the world as such betimes. Commented Nov 25, 2023 at 0:02
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    This question is incomplete. You need to describe what you mean by primary and secondary qualities and who you mean by one quality being abstracted from another. By my reading of the terms, (1) seems backward. If primary qualities are abstracted from secondary qualities, then primary qualities are ontologically dependent on secondary qualities. Commented Nov 25, 2023 at 1:36
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    Berkley based his arguments on Locke's theory of primary and secondary qualities, but Locke himself denied premise 3). To him, secondary qualities are powers or dispositions in objects to cause sensations in us rather than ideas in the mind, see Dicker, Berkeley's Attack on the Theory of Primary and Secondary Qualities. For the current state of the art on the question see Ross's survey Primary and secondary qualities.
    – Conifold
    Commented Nov 25, 2023 at 4:18
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    Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Meanach
    Commented Nov 25, 2023 at 13:07
  • Berkeley seems to clearly exhibit Motivated Reasoning. So the point of studying his work is not the work as such, but to understand what he was driving at.
    – Scott Rowe
    Commented Dec 3, 2023 at 0:10

3 Answers 3


His argument is rather likely saying that temperature is a construct of thermometers. Let's accept point 2) and agree that colours, scents and so on are mental constructs. Must it follow that daffodils and roses are mental constructs? Clearly in one sense a daffodil is a mental construct, in that of all the matter that comprises the Universe a daffodil is a subset singled out by human minds. But in another sense no- the matter has an existence, and would remain even if all humans died overnight. The daffodil has a definite mass that could be measured by a robot, and gives off light of particular frequencies which have well defined effects on photographic plates, and so on. There are many primary qualities which we do not directly perceive, and thus are independent of secondary qualities. Take the mass of the Earth, for example, or the charge density within a capacitor. Or take the first thirteen billion years of the evolution of the Universe, during which time it had no secondary qualities because there were no humans to perceive them. Or take gamma rays, x-rays, radio waves- they have no secondary qualities; do they therefore not exist?

Berkeley's worldview is interesting, rather in the way that solipsism is, because it seems patently nonsense but you might struggle to say exactly where are the faults in his reasoning. In relation to the summary you present in your question, the weak points are:

Primary qualities can be abstracted from secondary ones. We can have a high level of confidence about many aspects of reality, such as the mass of a neutron, say, even though we do not perceive them directly and they have no direct secondary qualities.

Secondary qualities arise because sensory inputs trigger activities in our brains, and we associate the secondary qualities with our ideas about the world. Ultimately, the sensory inputs arise from electromagnetic or electrostatic effects acting on parts of our bodies, which trigger a cascade of other events before a sensation is registered in the brain. All of those effects have primary properties that can be detected by non-human measuring devices. Indeed, you can take the view that the electrical effects that trigger the subsequent signals through our nerves do not in themselves have secondary qualities at all. A single photon from a daffodil does not have any of the secondary qualities you would associate with a daffodil. Berkeley has his ideas the wrong way around. There is a real physical world, and what we create in our heads is an illusory model of it, one no doubt developed and refined through evolution.


I thought of a few other scenarios that might be challenging to explain from a Berkeleyan perspective. Here are two which present two different issues...

Suppose we presented the good Bishop with two AA batteries, one charged and one not. Visually they would be undistinguishable. By looking at them, how would the Bishop determine which had the quality of being able to power a fluffy toy rabbit? This seems to me to represent a class of cases in which a primary quality is not unabstractable from secondary ones, seemingly being entirely independent of them.

Now let us present the mystified cleric with a pocket calculator, invite him to type ten random digits and then press the appropriate button to display the square root of the long number he had entered. The result shown on the screen would appear in Berkeley's mind as a secondary quality of the calculator; but if all of the calculator's qualities existed only in his mind, how would he account for the fact that pressing a button had caused him to imagine the correct answer to a mathematical problem that might have taken him a very long time to arrive at by cogitation alone? This seems to me to represent a class of cases in which a primary quality (eg a displayed number) would be impossible for the brain to arrive at through imagination.

Of course, it is rather unfair to accuse the Bishop of having overlooked examples based on technology that did not exist in his day, but leaving that aside, I cannot immediately see how I could account for those two scenarios (and others beside) in a way that sat easily with Berkeley's scheme.


Re. "(1) If primary qualities cannot be abstracted from secondary qualities, then primary qualities cannot exist apart from secondary qualities."

Argument 1 is countered by Heidegger in his statement:

Being, as the basic theme of philosophy, is no class or genus of entities; yet it pertains to every entity. Its 'universality' is to be sought higher up. Being and the structure of Being lie beyond every entity and every possible character which an entity may possess. Being is the transcendens pure and simple. (Being & Time, H.38)

Secondary qualities are necessarily separate from primary qualities. The quality of things cannot be in the foundation of things, (by the law of non-contradiction) otherwise thingness would be in its own foundation. The required foundation should not entail an infinite regress of thingness.

Note, this does not make suppositions about what Being is, only what it logically isn't.

Re. "(3) Secondary qualities are nothing but sensations or ideas that exist only in the mind."

Then the primary qualities (noumena) are what gives rise to the secondary qualities (phenomema). So Being is noumenal.

Conclusion: Secondary qualities exist only in the mind.

To elaborate, in Pathmarks (GA9), Letter on “Humanism” (1946) pages 252-253, Heidegger refers to being as the noumenal 'clearing', the concealed vista from which 'things' (phenomena) are discerned, mistakenly or correctly, so what is discerned is not necessarily what the vista contains. Representations are not necessarily straightforward (due to the twofold concealment).

metaphysics recognises the clearing of being either solely as the view of what is present in “outward appearance” (ἰδἐα) or critically as what is seen in the perspect of categorial representation on the part of subjectivity. This means that the truth of being as the clearing itself remains concealed for metaphysics. [163] However, this concealment is not a defect of metaphysics but a treasure withheld from it yet held before it, the treasure of its own proper wealth. But the clearing itself is being. Within the destiny of being in metaphysics the clearing first affords a view by which what is present comes into touch with the human being, who is present to it, so that the human being himself can in apprehending (νοεἴν) first touch upon being (θιγεῑν, Aristotle, Metaphysics Θ, 10). This view first draws the perspect towards it. It abandons itself to such a perspect when apprehending has become a setting-forth-before-itself in the perceptio of the res cogitans taken as the subiectum of certudio.

The noumenal nature of the clearing and its twofold concealment is clarified in Off the Beaten Track (GA5 ), "The Origin of the Work of Art" (1935-1936) page 31. In refusal discernment is difficult or impossible; in obstructing appearance is camouflaged or misleading. What is discerned is uncanny.

the clearing is pervaded by a constant concealment in the twofold form of refusal and obstructing. Fundamentally, the ordinary is not ordinary; it is extra-ordinary, uncanny [un-geheuer].

To emphasis that this is as metaphorical as it is noumenal there is a different approach in Time and Being (GA 14):

Is Being at all? If it were to be, then we would certainly have to recognize it as a being and thus find it as such among the other beings. This lecture hall is. This lecture hall is lighted. We immediately recognize the lighted hall as a being, But where in the whole hall do we find the “is”? Nowhere among the things do we find Being.

Derrida gives it a postmodern twist in Heidegger: The Question of Being and History, page 209

Being in general is nothing, but the multiplicity of beings and of types of beings could not be thought as such, beings could not be thought as such without pre-comprehension at least of the meaning of being in general.

Elusive primary qualities, Berkeley has my sympathies.


Berkeley makes his argument in the context of his time and his project. So here is another approach to your question. I hope it is helpful.

Just to give a little more detail and context to the argument, the SEP summary is based on Three Dialogues between Hylas and Philonous:-

… Hylas allows that color, taste, etc. may be mind-dependent (secondary) qualities, but contends that figure, solidity, motion and rest (the primary qualities) exist in mind-independent material bodies. The mechanist picture behind this proposal is that bodies are composed of particles with size, shape, motion/rest, and perhaps solidity, and that our sensory ideas arise from the action of such particles on our sense organs and, ultimately, on our minds. … Here Philonous has a two-pronged reply: (1) The same sorts of relativity arguments that were made against secondary qualities can be made against primary ones. (2) We cannot abstract the primary qualities (e.g. shape) from secondary ones (e.g. color), and thus we cannot conceive of mechanist material bodies which are extended but not (in themselves) colored.SEP - Berkeley 2.2.2

We can resist this argument by accepting the conclusion, adopting the SEP's suggestion (footnote 11 in the above article):-

One (Lockean) account of colour is as a (mere) power to cause ideas in us. On that account, bodies are in fact coloured and they would be coloured even in the absence of perceivers.

Berkeley himself seems to not to have much confidence in this argument. He says:-

In short, let any one consider those arguments which are thought manifestly to prove that colours and taste exist only in the mind, and he shall find they may with equal force be brought to prove the same thing of extension, figure, and motion. Though it must be confessed this method of arguing does not so much prove that there is no extension or colour in an outward object, as that we do not know by SENSE which is the TRUE extension or colour of the object. But the arguments foregoing plainly show it to be impossible that any colour or extension at all, or other sensible quality whatsoever, should exist in an UNTHINKING subject without the mind, or in truth, that there should be any such thing as an outward object. Berkeley Of the Principles of Human Knowledge §15.

So the force of his argument depends on his thesis that no “unthinking” object can exist “without” the mind. That’s another issue, but there are arguments to that effect. See SEP - Sense Data §3

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