(1) George Berkeley’s (1685–1753) theistic subjective idealism (or immaterialism) that invokes a god of classical theism as the “greater mind” that creates both finite minds and the ideas given to minds, orIt is interesting that Berkeley’s idealism was clearly directed both against (1) the radical skeptics of his day and (2) the materialist atheists (Grayling 2005: 166–167).
(2) a non-theistic idealism that is agnostic about what the “greater mind” actually is.
For the empiricists of Berkeley’s era had opened up profound epistemological problems by stressing the differences between
(1) appearances (our conscious experiences and sensations), andIn the terminology of Berkeley, there is thus a gap between (1) human “ideas” and (2) “things” (of the external world) (Grayling 2005: 168). Our internal sensations (or ideas) do not give us direct access to the external world, so how can we have knowledge of it? The latter was the question asked by radical skeptics.
(2) reality (some posited external world).
Berkeley’s answer was to simply argue that the material “things” of the external world do exist (Grayling 2005: 168): only ideas and minds exist. Therefore we have direct experience of ideas – the only things that exist apart from minds.
Under Berkeley’s idealism, god is the external cause of finite human minds and the consistent and non-illusory ideas we have. For, given that there are many consistent ideas not under our control, Berkeley admits that the order seen in such consistent ideas must have some systematic cause: hence it is god (Mackie 1982: 71).
One of Berkeley’s maxims is the idea that “to exist is to be perceived” (or in Latin esse est percipi), and thus our existence and the ideas of our conscious life are causally dependent on god’s “perception.” Thus, for example, Berkeley accepts that the table in your kitchen still exists when nobody is in the room perceiving it, because it is still perceived by god.
By contrast, the non-theistic idealist does not necessarily need a god of classical theism, just a “super-mind” or “uber-consciousness” that is the cause of our finite human minds and our ideas. In what follows, I will refer to the non-theistic idealist’s greater mind as the “super-mind.”
I argue that these are crucial points in any debate with idealists:
(1) Epistemologically speaking, the idealist is in the same fundamental position as the indirect realist materialist: the idealist posits an external and directly unobserved cause of our given consistent ideas and perceptions. For neither (1) the external world of realism nor (2) the god or “super-mind” of idealism is directly observable or directly experienced in immediate conscious life.I think I have already explained (1) and (2) above, so let us proceed to (3), (4) and (5) below.
Now I stress that this is not necessarily a problem for the idealist, but it is an important observation that means that in this respect the idealist position is not epistemologically superior to the realist one;
(2) Epistemologically speaking, the idealist – unless he can provide a valid and sound deductive argument or arguments – must use inductive arguments on the basis of indirect evidence to prove his hypothesis of a god or “super-mind.”
But that means, epistemologically speaking, that the idealist and the realist are also on the same ground, since the indirect realist’s belief in an external world is also an inductive inference on the basis of indirect evidence.
So again in this respect the idealist position is not epistemologically superior to the realist one, but on a par;
(3) Berkeley’s argument that “an idea can be like nothing but an idea” is unconvincing;
(4) Berkeley’s theistic god is a clear weak point in this theory, and it is not a simpler theory than realist materialism;
(5) on many issues, idealism of any type has weak explanatory power and often no explanatory power at all.
(3) An idea can be like nothing but an idea?
Berkeley makes this argument in The Principles of Human Knowledge, section 8.
J. L. Mackie shows why the indirect realist position is not refuted by Berkeley:
“… that an idea can be like nothing but an idea, collapses when we see what sort of likeness or resemblance the materialist view requires. This is just, for example, that when I am in a perceptual state whose content is describable by saying that I seem to be seeing something square, there should be something that is (approximately) square. Or again, that when it is with me as if I were seeing two objects of similar shape and size, say two billiard balls, there should really be two similarly shaped and sized objects in the neighbourhood. The likeness or resemblance required is just that where the content is as of an X, the reality should be (roughly) an X. There simply is no a priori impossibility or even implausibility about something other than an idea being like an idea in this sense.” (Mackie 1982: 72).Perfect or exact resemblance between our sensory states and objects of the real world is unnecessary for the indirect realist position.
All we need is (1) an approximate similarity and/or (2) a relationship of causal dependence from objects in the external world running to some of our sensations, which does not exclude that, in a modern scientific sense, the object of the external world that is the causal origin of some perception has many properties not observable to us.
(4) Berkeley’s theism is fraught with difficulty
Berkeley’s idealism is based on a theistic conception of human minds: that humans are created by a god, and (presumably) fundamentally different from animals.
First, a problem here is: do animals have minds? How does the idealist offer an answer to this question? It is not clear what Berkeley thought (Cummins 2005: 190).
Secondly, as we have seen, for Berkeley god is the external cause of the regularity in many of our ideas.
So Berkeley needs to prove the existence of god. But the history of attempts to use deductive arguments for the existence of god is one of utter failure (and I rely on Michael Martin’s  survey and critique here), so Berkeley’s argument must fall back on inductive arguments.
The problems with Berkeley’s actual argument for god are well known (Mackie 1982: 64–80). For one thing, the cause of the consistency of the ideas beyond our control might not be unitary. Why can’t it be explained by many “super-minds” or panpsychism? (Mackie 1982: 71).
Even if we put all those difficulties aside, there is still a severe problem: the hypothesis of a theistic god is much more complex and more extravagant than a realist materialist hypothesis.
Berkeley, of course, argued that his idealist hypothesis with a god was the simpler explanation invoking Occam’s razor. But this contention is unconvincing.
Consider the attributes of the god of classical Judeo-Christian theism, with additional ones required by Berkeley:
(1) god is a personal and conscious mind;I submit to you that these attributes make the god invoked by Berkeley an extremely complex entity, possibly the most complex thing you could postulate.
(2) god is omnipotent;
(3) god is omniscient;
(4) god is perfectly good;
(5) god constantly maintains the existence of finite minds and their ideas in a process we can’t understand but which appears miraculous.
In fact, there is still debate about whether properties like omnipotence, omniscience, and perfect goodness in one being can even be logically possible (Martin 1990: 278–316).
By contrast, look at the attributes of a real physical universe as postulated by science:
(1) the external universe of matter and energy is not conscious nor it is a personal entity, and in this respect is a simpler entity than a theistic god;One can add that the realist materialist view also explains evil and suffering in a far better way than theistic idealism, amongst its many merits.
(2) following from (1) the universe is not omnipotent, omniscient, nor perfectly good, and in this respect is a simpler entity than a theistic god;
(3) the universe consists of matter and energy and its relations governed by a limited set of regularities we call “physical laws,” which can be discovered by humans through inductive and experimental science. Thus the external universe is a simpler entity than the miraculous powers of a theistic god.
(4) all complex things in the universe like life and minds have been built up and created over many billions of years by relatively simple and well understood processes like Darwinian evolution by natural selection. The existence of minds does not require some inexplicable miracle, but is explicable under a realist materialist view.
In short, the realist materialist position is the simpler and better explanation – and, under the principle of Occam’s razor, the preferable one.
Furthermore, even Berkeley’s master argument, if it is really taken to be a devastating argument against the existence of a real external world of objects, would apply to other minds and to the “super-mind”:
“Secondly, if the [sc. Master] argument were sound, it would prove too much. Although … [sc. Berkeley] states it with regard to sensible objects like houses and books, their nature as sensible objects plays no part in the argument; so, if it held at all, it would hold equally against the suggestion that I can conceive that there are minds that are not conceived by me; thus it would establish solipsism, in which I would reject as not even conceivable the existence not only of material things but also of other minds and spirits, including God, except in so far as they are conceived by me. This line of argument is, therefore, not only fallacious but also, in these two ways, misdirected.” (Mackie 1982: 68).That is, think of a mind that you do not perceive now. There is a vast amount of empirical evidence that other minds exist even though you do not perceive them.
But if we cannot conceive of a mind without it being perceived, it follows that in any initial thinking through idealist philosophy, you have no good reason to think any minds exist that you do not immediately perceive. But, says Berkeley, god perceives them, so they do exist. But Berkeley’s argument works just as well against god or the “super-mind”!
If we have no direct perception of the “super-mind,” who perceives the “super-mind” and causes its existence? And who perceives the “super-super-mind,” and so on?
That is, Berkeley’s philosophy must cut off an infinite chain of explanation by positing “god” or the “super-mind” as a “brute fact” that is inexplicable. But, in that respect at least, it is no better than a materialist viewpoint that posits the universe as the ultimate “brute fact,” the difference being, as we have seen, that the hypothesis of a real universe is simpler and by Occam’s razor a better hypothesis.
(5) Realist Science has great explanatory power and Idealism does not
Our natural sciences have produced a vast set of theories that explain the world we experience, and under the indirect realist interpretation we can posit an external world of real objects of matter and energy affected by forces.
As just a sample, consider the following theories:
(1) the Big Bang theory;If one takes an idealist view, whether Berkeley’s or a non-theistic idealism, none of these theories can be literally true, for there is no external word of matter and energy.
(2) the theory of the development of gases, stars, planets and galaxies;
(3) the theory of the origin of life by biochemical processes;
(4) the theory of Darwinian natural selection acting on self-replicating biochemical compounds and living things, producing a great diversity of life over many billions of year on earth;
(5) the theory that human beings evolved from lower life-forms and that various types of minds too evolved gradually and incrementally as a product of evolution.
Minds were created by god or the “super-mind” and did not arise by gradual material processes.
But we have a vast amount of empirical evidence available to our senses that can be used in inductive argument to support the truth of these theories.
Our realist materialist science has a strong explanatory power explaining the wealth of data we see, but idealist philosophy – whether of Berkeley or a non-theistic idealism – has weak explanatory power and often no explanatory power at all.
This point is very easy to prove, I think.
We need only think of fossils. Our conscious life presents to us things we call fossils, and by inductive inference we infer that they are the remains of living things long dead. A realistic materialist science explains what fossils are, and indeed can use them to reconstruct a history of life on earth: things that really existed in an external world, including a specific long line of animal life forms from which human beings are descended.
But what explanation can an idealist offer for fossils? As we have seen the idealist faces difficulties answering the question whether higher animals even have minds. If animals do not have minds, then they must be mere “ideas” given to the mind by god or the super-mind. I feel certain that no idealist would content that plants have minds, so how does the idealist explain plant fossils?
What explanation can the idealist give under his theory, except to say it is another mystery?
And why has god or the super-mind given us a wealth of sensory ideas that lead us to inductively infer that our “world” once had living animals and plants now dead? Is god or the super-mind engaged in deception and fraud? If so, why?
Or take another example: why is it that some people have different perceptions of colour? (e.g., colour blindness). Why does god or the super-mind that create minds with different types of colour perception?
A realist materialist gives us a clear explanation: colour blindness is either (1) genetic and a problem with genes or (2) caused by certain diseases.
Again and again, I contend we can find endless puzzling problems from our conscious life that realist materialist science gives a powerful explanation of, but which cannot be adequately explained by idealism.
Philip Pilkington has a response to me on idealism here:
Philip Pilkington, “The Mystery of Matter: A Response to Lord Keynes on Berkeley’s Idealism,” Fixing the Economists, February 27, 2014.
Cummins, Phillip D. 2005. “Berkeley on Minds and Agency,” in Kenneth P. Winkler (ed.), The Cambridge Companion to Berkeley. Cambridge University Press, Cambridge and New York. 190–229.
Dicker, Georges. 2011. Berkeley’s Idealism: A Critical Examination. Oxford University Press, Oxford and New York.
Grayling, A. C. 2005. “Berkeley’s Argument for Immaterialism,” in Kenneth P. Winkler (ed.), The Cambridge Companion to Berkeley. Cambridge University Press, Cambridge and New York. 166–189.
Mackie, John Leslie. 1982. The Miracle of Theism: Arguments for and against the Existence of God. Clarendon Press, Oxford.
Martin, Michael. 1990. Atheism: A Philosophical Justification. Temple University Press, Philadelphia.