Another major philosophical view is idealism: the theory that reality is mind or mind-like, and that material things are appearances of this reality to consciousness. This is the view I aim to defend. Most classical European philosophers have accepted some form of it. It was most fully formulated by German philosophers like Kant and Hegel, and it dominated British philosophy in the early twentieth century. Immanuel Kant was especially influential, and he is still taught in most philosophy courses today. Kant thought that reality-in-itself is completely unknowable, but that human thought constructs reality-as-appearance (as we see it), and that human reason compels us to think of persons as free moral agents, not determined by the material world. Materialism, Kant thought, confuses appearance with reality. So even though we cannot know reality-in-itself, we must think of it as personal.
As I approach the topic of philosophical idealism, I will begin with some major philosophical questions raised by the natural sciences: does the objective world really consist only of the basic properties identified by physics? Is it governed by universal and unbreakable laws? Do those laws determine everything that happens, so that no alternatives are even possible?
Affirmative answers to these questions are very ambitious dogmas or postulates indeed; and they could not be confirmed by observation. We cannot observe the unobserved; we cannot be sure that laws of nature are never broken; and we can never know that nothing could have happened except what did happen. The postulates that physics can accurately and adequately describe what the unobserved world is like, that absolute laws of nature in some mysterious sense exist, and that there is one and only one possible effect of every cause, seem to be oddly arbitrary. Why should it be so?
Perhaps these are the basic postulates which helped modern science to get going. Only if we think that the human mind is capable of understanding the structure of nature, only if we think that there are mathematically describable laws or general principles of causality in nature, and only if we think that causality is universal, so that there is always a reason why anything happens, that nothing happens that cannot be accounted for by reference to some general rational principle, is modern science possible. These are, as Immanuel Kant put it, necessary conditions of the possibility of natural science (at least of a Newtonian sort).
But there is a paradox about these postulates. They give human thought and imagination a central role in comprehending the nature of reality. Human thinking, especially in inventing systems of mathematics and in devising cunning experiments to see how nature behaves, is assumed to be adequate for an understanding of nature.
But can we trust human reason? “Reason is the slave of the passions,” said David Hume. How can we have the arrogance to think that the petty human mind – the product, according to some evolutionary views, of millions of random genetic copying-mistakes and accidents – is capable of understanding the origin of worlds or the ultimate nature of things? Perhaps, said Hume, we should accept that habit or custom controls human conduct. We just think the way our brains are set up to think, and they are set up that way, because brains with those thoughts in them have enabled organisms to survive and reproduce better than brains without such thoughts. Hume did not know about evolution. But he certainly would have approved of it, since he believed that enlightened Scottish intellectuals were more evolved than the common herd of humanity.
Brains that thought that you could never predict what was going to happen next died out, because they never learned from experience. Only brains that assumed the future would be like the past had the sense to flee from predators, and only those brains survived. Over many centuries a stock of common-sense beliefs builds up, simply because brains without those beliefs get wiped out. Such beliefs would include the belief that there are predators out there even when you don’t observe them (the principle of objective existence), that predators are going to behave in regular and more or less predictable ways (the principle of induction), and that the same predator always produces the same effect – namely, once you are caught you will be eaten (the principle of efficient causality).
Of course this is just a way of saying that true beliefs tend to be more useful than false beliefs. The reason these sorts of beliefs have survival-value is that they are true; they say what reality is like. You could say that the beliefs are based on long and repeated observations by many people, some but not all of whom got eaten. They are not just abstract rational principles, thought up in some primeval cave.
I was once asked to contribute the section on philosophy in a Reader’s Digest book, The Last Two Million Years. I agreed to write the first half and, before the commissioning editors had quite realized what was going on, collected quite a nice fee for saying, correctly, that as far as we know nothing happened in philosophy for the first million years. They nevertheless produced some pretty pictures from the Lascaux Caves, which perhaps could, by a large stretch of the imagination, be called philosophical (that is to say, nobody is quite sure what they are about). Regrettably I missed the opportunity to write a chapter on Neanderthal philosophy, which did not, as it turned out, have a very good survival-value.
Toward the unknown
Returning to the question of basic evolved beliefs, the point remains that these beliefs go well beyond simple observation. They begin from observations, but what they do is organize our sense-perceptions so that we interpret these perceptions as perceptions of entities which have objective existence, which threaten, entertain or eat us, and which behave in more or less predictable ways. Such organizing principles are not arbitrary, since they can help us to eat other things before they eat us – a skill at which humans are remarkably adept.
These principles no doubt form the basis of the more science-based principles of objectivity, causal law, and determinism. They are nonetheless very different. Common sense sees the world as consisting of predators and prey, not atoms and molecules. We see that predators behave in more or less regular ways, without thinking that they obey universal laws of nature. We think that we can sometimes escape the predator’s leap, not that there is no alternative to being eaten. The idea of a Newtonian reality of deterministic and universal law is a leap of imagination that was first clearly formulated by Newton himself, even though it was presaged by some late medieval philosophers, as a combination of ideas of predestination and the creation of the universe by a rational all-determining being.
Moreover, the Newtonian picture omits entirely some other human basic evolved beliefs. Early humans developed a “theory of mind”, that other animals have purposes and intentions partly hidden from us, but helping us to predict what they will do next. They developed a principle of reciprocity, that you can never quite be sure how other animals will react to you, but your attitude to them will be an important factor in how they subsequently behave. They developed a principle of responsibility, so that on many occasions you can choose between alternative actions, and you are responsible for that choice.
All these natural principles are hard to accommodate in a Newtonian scheme of nature. Minds, personal relationships, and free actions, are all alien to a wholly mechanistic view of objective reality. Yet it is precisely in scientific investigations that we must assume the importance of understanding and imagination, the cumulative cooperation of many meaningfully communicating minds, and the free selection of experimental conditions and mathematical axioms that will enable us to understand the physical world better.
Is it plausible to consider all this as a higher-order by-product of the unconscious, mechanically determined, exclusively rule-driven behaviour of huge numbers of fundamental particles, each of which is identical in nature to every other of the same sort? Locke baulked at the thought, as had Descartes before him. Thus they were driven to introduce minds into a Newtonian mechanistic scheme that left no room for them. Having constructed the machine of nature, they then had to introduce ghosts to pull the levers of the machine. But how insubstantial ghosts could pull solid material levers, or even where exactly the levers were to be found, remained a mystery.
Perhaps the solution is not to get rid of the ghosts, but to dismantle the machine and start again. That is precisely what happened in the early twentieth century with the advent of quantum mechanics. The machine itself began to disappear. Ryle and Wittgenstein had that thought, too. But they preferred to bypass the findings of the new physics, and to resort to the sort of common-sense beliefs that had preceded physics, and that left questions of the nature of reality as pseudo-problems that could be ignored.
Some physicists agree and regard philosophy as a waste of time. We can do the maths, make the predictions, construct the nano-devices. But we do not need to give any theoretical interpretation to what we are doing. Others, however, feel the need to relate our mathematical computations to our understanding of the world, and to answer the question of what the world is objectively like. But maybe what quantum physics suggests is that the question is unanswerable. For quantum physicists like Bernard d’Espagnat objective reality is forever “veiled” from human knowledge, and all we can know is how things appear to us when we observe them (when we collapse wave-functions) in laboratory conditions. Perhaps there is no way of knowing what reality is like in itself, apart from human observation of it. We know how the world appears to us, but its inner reality remains forever veiled. That possibility introduces my sixth philosophical theory about what the world is really like, the theory that human knowledge is confined to how the objective world appears to our minds and senses, but that the world in itself is wholly unknowable. Nevertheless, in some sense the world as we know it is a product of mind. In the history of philosophy, that is the view of Immanuel Kant, who called it “transcendental idealism”, but in his later writings said that he preferred the phrase critical idealism (Theory 6).
Immanuel Kant and unknowable reality
Most classical philosophers have been idealists – they have thought that the ultimate character of reality is mind-like. But in modern philosophy the most influential name is that of Immanuel Kant. If we want to trace the roots of modern forms of idealism, we have to start with Kant. There is quite a lot of misunderstanding of his views – he is thought to have undermined the possibility of metaphysics and to have destroyed all arguments for God, for example. On the contrary, his aim was to place metaphysics on a firm footing, and to defend belief in God as rationally necessary (though not founded on theoretical arguments about causality).
Kant’s views are very complex, but it is worth exploring them, as they provide the basis for taking modern idealism seriously. He held that space and time themselves, which seem so objective, are in fact forms of our intuition. That is, they are a framework the mind constructs to build a map in which our sense-perceptions can be located. The map is mind-constructed, and if we take away mind, we have no way of saying what is left. This may seem an extremely odd view, but it receives some corroboration from modern physics. In quantum physics our view of space as a three-dimensional Euclidean container, and of time as a kind of cosmic clock which ticks at an absolute rate, adding second to second as we pass through it, is a purely subjective condition of our perception, which does not copy what objectively exists. Quantum physicists tend to say that space-time is non-Euclidean, and is part of a multi-dimensional reality in which space and time may become, under certain conditions, interchangeable. Superstring field theorists say that space and time are perceptually selected fragments of a ten-dimensional hyperworld, and do not exist objectively as the Euclidean space and flowing time that we perceive them to be. Such things can be mathematically expressed, but if we try to imagine what such a strange world is like, imagination fails. Things in themselves are totally beyond our categories of thought.
It seems, then, that the whole of experienced space-time, and everything in it, is a construction of the mind, and would not exist without the mind. Some philosophers talk about “constructions of the brain” rather than constructions of the mind. But that is a fairly crude mistake, since the brain is a material thing in space-time, and therefore cannot be what constructs the reality of experienced space-time. The brain, like all material things, is a construct of the mind and would not exist as it appears to us without that constructive activity of the mind. So the world as we see it is not a construction of the brain, but the world as we see it (including the brain) is a construction of the mind.
That is enough to refute the simple materialist view that nothing exists, or even can exist, outside of space and time. Beyond observed space-time, there are at least two things. One is the unknowable world of things in themselves and the other is the mind that constructs the world of appearances, by its creative interaction with things in themselves.
But if the mind is not an appearance (since it constructs the world of appearances), it must be a thing in itself. Or, to be more precise, what appears to us as the constructive activity of the mind in producing the world of appearances, is also an expression of an entity in the world of things in themselves.
Even if the mind as we experience its activity is an appearance, it is as real an appearance as the world of physical objects we sense. It is not the case, as Gilbert Ryle seems to say, that physical objects (bodies) are obviously real, whereas minds (creative intellectual acts that constitute the world of sense-perceptions and thoughts) are ghosts. On the contrary, both bodies and minds are appearances of an objective reality. They have an equally real (or unreal) status.
The personal world
Ryle would of course object that this is even worse than Cartesian dualism. His view is that in the Cartesian world we never know what is going on in other minds. Minds are locked in permanent isolation and never meet. But at least bodies meet. That is enough. We do not need these private islands where minds spend their lives in solitary confinement.
The Kantian world is much worse. Not only are minds in isolation. The whole of the experienced world is put into isolation, minds, bodies, and all. People cannot ever get out of their own private worlds or know what is going on in anybody else’s world. Bodies never meet, for bodies are just parts of essentially private worlds. We are condemned forever to never meet anyone else, and never to know what is really going on. All of us are condemned to permanent ignorance and illusion, from which there is no escape. Is that better than Descartes?
Ryle is right. We cannot have a world in which knowledge depends upon making untestable inferences to hidden processes. But Kant does not think that we make inferences to the external existence of objects. Kant proposes that from the very first we interpret what we experience as experience of a world of objects. Our interpretations of the world are not just passive receptions of inert sensations. We are not faced with a lot of private sensations from which we subsequently have to infer the untestable assumption of an external world and other people. Experience is in a sense not shared with anyone else. But that is a realization that comes only from the much later sophisticated reflection that not everyone sees the world as I do.
From the very first, Kant argues, human thinking is an active power that necessarily interprets experience as experience of a world of continuing substances in causal interaction. That is, we interpret the coloured shapes we see as appearances of external objects which we encounter through these perceptions. This is a basic interpretative activity of the mind. We do not see sensations. We see objects, presented to us via sensations. Experience comes to us already interpreted by thought. We are aware both that something beyond our control is given to us in experience, and also that thinking actively interprets that “something” as a world of causally interacting substances. We are never isolated and alone. On the contrary, we are always encountering other objects and actively responding to them. We are active agents in a world of active agents. That is not an inference; it is a necessary condition of the possibility of knowledge, both in science and in everyday experience of personal relationships.
To know anything you need both perceptions – sensory data – and concepts – thoughts. So of the world beyond our perceptions, of reality in itself, there can be no theoretical knowledge. This is the proper reply, Kant thinks, both to common sense (naive) realists and to reductive materialists. They both think they know what there is, but both are mistaken. Kant does not know what there is (not theoretically, anyway). But, whatever it is, it must produce the appearances we see and the active minds that interpret them. There is a hidden reality, and the mind plays a positive creative role in interpreting its appearances. This provides the key to understanding what Kant always regarded as the most important, and most misunderstood, part of his philosophy: that which reason forbids me to know, reason compels me to believe.
The limits of reason
Kant argues that if reason claims to tell the truth about ultimate reality it leads to contradictions (he calls these “antinomies”). But we do know that if there are appearances, then there must be a reality that appears. In the world of appearances, we seek determining causes for everything. We actually insist that nature conforms to our demand for causes for all events. It is a condition of the possibility of scientific knowledge of the world that we think of the world as consisting of continuing substances in a succession of regular and predictable causal relationships. That is no mere whim, as if it were no better than being inclined to think of the world as moved about by the arbitrary acts of millions of fairies. These inclinations are rational, because they are the very conditions of the possibility of our understanding of an intelligible world. And they are confirmed by constant experience, as science continually finds out more about the natural world.
Just as reason (or understanding, in Kant’s terminology) lays down the conditions of the possibility of scientific knowledge, so reason lays down the conditions of a complete rational explanation of the world, including the non-scientific facts of subjective consciousness, freedom, value, and purpose. These conditions cannot be completely confirmed by any specific experience, so they remain postulates – not irrational leaps of faith, but rational postulates that cannot be fully confirmed by experience.
The postulates of reason, according to Kant, have both a negative and a positive sense. In their negative sense, they show that materialism, naturalism, and fatalism are indefensible, according to Kant’s Prolegomena to any Future Metaphysic. Materialism is the view that the mind is nothing but a material thing, whereas Kant shows, he thinks, that it is the part-creator of reality-as-appearance. Naturalism is the view that nature is self-sufficient, whereas Kant shows that nature is the appearance of an underlying and unknowable reality. And fatalism is the view that all human acts are products of blind necessity, whereas Kant shows that they may indeed be free in reality, even though we can never prove that they are.
To many philosophers, it sounds impressive to say that the experienced world is only an appearance of a very different underlying reality. But it is not quite so impressive when it is added that we know nothing at all about such a reality. Kant’s position of complete theoretical agnosticism about the world of things-in-themselves does not quite ring true.
The leap of reason
It is at this point that “faith” comes into the picture, and gives a positive sense to the postulates of reason. Faith, for Kant, has absolutely nothing to do with revelation or religious authority, both of which he hated so much that he never went to church and regarded kneeling down to pray as an affront to human dignity. Kant was a great defender of autonomy, of deciding things for yourself, and he tried to get all his disciples to take his word for it that they should decide things for themselves. He added of course that if they decided correctly, they would all agree with him, since he always made the most rational decisions. Insofar as they disagreed, they were not being fully rational.
Kantian faith is the positive acceptance of the unprovable but fully rational postulates of reason on practical or moral (not religious) grounds. Kant wrote three “critiques of reason”, in which he set out to show the limits of reason and its positive role in human thought. At this point I am only concerned with the first two critiques. His first critique, the Critique of Pure Reason, was concerned with examining the role of theoretical reason in helping us to achieve knowledge in science. He argued that it is a condition of the possibility of doing science that you accept some necessary postulates of understanding (most importantly, the objective existence of substances and of causality).
His second critique, the Critique of Practical Reason, went on to discuss the role of reason in practical action and especially in morality. He argued that it is a condition of the possibility of morality that you accept some postulates of reason (most importantly, the objective existence of free agents who are able to act on rationally chosen principles). Having shown that science does not give a theoretical account of things-in-themselves, he now suggests that morality gives a special sort of insight into that veiled reality. At least it compels us to think of it in a particular way (as a world of free agents), even though we cannot theoretically establish our beliefs.
Reason thus plays a positive role in human knowledge. In theoretical matters it requires sense-experience to confirm its postulates. But humans not only think and understand. They also act and set and pursue goals that they believe to be good. Is this a function of reason also? Can reason set goals of action, and are we free to pursue them? For Kant, reason does set two general goals of action – the happiness of others and one’s own perfection, “the fullest use of one’s free powers”.
But if reason sets such goals, then reason must be assumed to possess a causal role in the world, setting goals of action which I can then pursue. This entails two beliefs – that I am free to set and pursue rational goals and that it is possible to achieve them (otherwise it would not be a rational pursuit). Thereby results one of Kant’s major conclusions: I can never theoretically prove the human will is free. But for rational action and moral commitment to be possible, I must presuppose freedom in practice. Whatever my theoretical indecisions, I must commit myself in practice, and I know that I should commit myself to the wholly good.
Moreover, if I really think free commitment to realizing goodness is reasonable, I must believe that the good – which consists of both happiness and that form of self-cultivation which is virtue – is achievable, even in a corrupted world. Kant’s point is that if moral action is to be fully reasonable, and not just a matter of arbitrary decision, I must assume that what I am trying to achieve is possible. So fully rational moral action must commit itself to the hope that a world in which happiness is realized in accordance with the practice of virtue can and will exist. That is a presupposition of the rationality of the real world to which the human will commits itself in genuine moral action. For if reality is rationally structured, it will exist in order to realize an envisaged good, and the realization of that good is assured by the rational order of reality.
Kant is not, after all, a total agnostic. He believes there can be no knowledge or proof of the nature of the world beyond the senses. But he knows there is and must be such a world. The world of appearance is a world constituted by both an unknown objective reality and the constitutive activity of the mind, which in itself is also unknown.
But where theory may hesitate, persons must act. This is not as far from Hume as it may seem. Hume also is sceptical about transcendent metaphysical truths obtainable by reason. Hume also thinks we must act on the basis of our human sentiments and habitual inclinations to believe. But whereas Hume thinks that we are driven by passions and habits, which we cannot help, Kant insists that there are rational goals of action, that human persons are free, autonomous (capable of direction by their own free decisions), and that we must assume (without theoretical proof) whatever is necessary to embrace that freedom.
In this way Kant qualifies his view that we can know nothing of reality in itself. Though that is true of theoretical or testable knowledge, in moral action we commit ourselves to thinking of objective reality in a specific way, as a realm of autonomous rational agents. The limitation of theoretical knowledge to appearances means that such a commitment cannot either be established or disproved theoretically. In that situation, practice takes priority over theory, and, as Kierkegaard was later to put it, we may passionately commit ourselves to what is theoretically uncertain. For Kant, such passionate commitment is not irrational or non-rational. It is supremely rational and a condition of accepting the reasonableness of human moral freedom. It is a leap of reason, not a leap of faith.