Think: A Compelling Introduction to Philosophy

by Simon Blackburn

In the end, it is ideas for which people kill each other. It is because of ideas about what the others are like, or who we are, or what our interests or rights require, that we go to war, or oppress others with a good conscience, or even sometimes acquiesce in our own oppression by others. When these beliefs involve the sleep of reason, critical awakening is the antidote.

An argument is valid when there is no way—meaning no possible way—that the premises, or starting points, could be true without the conclusion being true (we explore this further in Chapter 6). It is sound if it is valid and it has true premises, in which case its conclusion is true as well.

rationalism: the power of pure unaided reason. For the rationalist can see from her armchair that things must be one way and cannot be other ways, like the angle in the semicircle. Knowledge achieved by this kind of rational insight is known as ‘a priori’: it can be seen to be true immediately, without any experience of the way of the world.

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At this point some suppressed premises suggested by the history of ideas may be used to excuse Descartes. He was undoubtedly more optimistic about the trademark argument than we can be because he inherited a number of ideas from previous philosophical traditions.

Nevertheless, isn’t there an awful hole in his procedure? What happened to the Demon? Might not even our clear and distinct ideas lead us astray? To close off this possibility, it seems, Descartes turns round and uses God—the God whose existence he has just proved—as the guarantor that what we perceive clearly and distinctly must be true.

It was one of his contemporaries, Antoine Arnauld (1612–94), who cried ‘foul’ most loudly at this point, accusing Descartes of arguing in a circle, the infamous ‘Cartesian circle’.

This is itself an interesting form of suggestion, and introduces a very important truth, which is that very often we are more certain of particular verdicts than we are of the principles that we might cite when we try to defend them.

For our purposes, we can leave this issue. What remains clear is that there is a distinct whiff of double standards here. The kind of sceptical problem embodied in the Evil Demon is somehow quietly forgotten, while Descartes tries to engineer his way off the lonely rock of the Cogito. And this might suggest that he has put himself on a desert island from which there is no escape.

David Hume

The Cartesian doubt, therefore, were it ever possible to be attained by any human creature (as it plainly is not) would be entirely incurable; and no reasoning could ever bring us to a state of assurance and conviction upon any subject. If Descartes’s project is to use reason to fend off universal doubt about the truthfulness of reason, then it has to fail.

The self-corrective nature of our systems of belief, mentioned above, is all we need. We could call this approach non-rational or natural foun-dationalism. (Not of course implying that there is anything irrational about it. It is just that the things in the foundation do not have the demon-proof way of ‘standing to reason’ that Descartes had hoped for.) Hume himself gave a number of arguments for side-lining any appeal to rationality, and we visit some of them in due course.

The emphasis on natural ways of forming belief chimes in with another strand in Hume and other British philosophers of the seventeenth and eighteenth centuries, which is their distrust of the power of unaided reason. For these philosophers, the best contact between mind and the world is not the point at which a mathematical proof crystallizes, but the point at which you see and touch a familiar object. Their paradigm was knowledge by sense experience rather than by reason. Because of this, they are labelled empiricists, whereas Descartes is a card-carrying rationalist. The labels, however, conceal a lot of important detail.

And what of the Evil Demon? On this story, the true moral of Descartes’s struggles is that if we raise the question whether our experience and reasoning (en bloc) accords with the way the world is (en bloc), it will take an act of faith to settle it. ‘God’ simply labels whatever it is that ensures this harmony between belief and the world. But, as Hume says in the passage just quoted, we do not find a need to raise this question in normal life. The hyperbolic doubt, and the answer to it, is in this sense unreal.

However, one piece of optimism is available to us, two centuries later. We might thus suppose that evolution, which is presumably responsible for the fact that we have our senses and our reasoning capacities, would not have selected for them (in the shape in which we have them) had they not worked.

The harmony between our minds and the world is due to the fact that the world is responsible for our minds. Their function is to represent it so that we can meet our needs; if they were built to represent it in any way other than the true way, we could not survive.

A rather different response shrugs off the need for any kind of ‘foundations’, whether certified by reason, as Descartes hoped, or merely natural, as in Hume. This approach goes back to emphasizing instead the coherent structure of our everyday system of beliefs: the way they hang together, whereas the sporadic experiences or beliefs we get in dreams are fragmentary and incoherent. It then points out an interesting feature of coherent structures, namely that they do not need foundations.

Otto Neurath (1882–1945)

We are like sailors who on the open sea must reconstruct their ship but are never able to start afresh from the bottom.

This approach is usually called ‘coherentism’. Its motto is that while every argument needs premises, there is nothing that is the premise of every argument. There is no foundation on which everything rests.

It is good, then, to remember four options in epistemology (the theory of knowledge). There is rational foundationalism, as attempted by Descartes. There is natural foundationalism, as attempted in Hume. There is coherentism. And brooding over all of them, there is scepticism, or the view that there is no knowledge.

Bertrand Russell (1872–1970)

THE MORAL How then should we regard knowledge? Knowledge implies authority: the people who know are the people to whom we should listen. It implies reliability: the people who know are those who are reliable at registering the truth, like good instruments. To claim knowledge implies claiming a sense of our own reliability. And to accord authority to someone or some method involves seeing it as reliable.

Hence, scepticism permanently beckons, or threatens, us. We may be tracking the world reliably, but we may not.

This part of Descartes’s doctrine marks him as a ‘substance dualist’. It is not just that there are two kinds of properties (mental properties and physical properties) and that persons can have both. It is that there are two kinds of bearers of properties as well.

People who hold that there are two kinds of property (mental and physical) but that they can belong to the one kind of stuff (whatever large animals are made of) are called property dualists.

Gilbert Ryle (1900–76)

You might say: all right, let us suppose these are wide-open possibilities. Perhaps I can never really know what the mind of another person is like, what mental events occur within it, or even whether there is any mental life going on at all. But can’t I still suppose that other people’s mental lives are much like mine? Can’t I reasonably use myself as a model for all the rest? It would be not so much a case of knowledge as of a hypothesis or conjecture, but it perhaps it is a reasonable conjecture to make. This is called the argument from analogy to the existence of other minds. The problem with this argument is that it seems incredibly weak.

Ludwig Wittgenstein (1889–1951)

Here they are being used to test the conception of mind and matter that gives rise to them. The argument is that if mind and matter are thought of in the Cartesian way, then there would be wide-open possibilities of a bizarre kind, about which we could know nothing. So, since this is intolerable, we should rethink the conception of how things are (this is called the metaphysics). A better conception of mind and its place in nature should foreclose these possibilities. The aim is not to wallow in scepticism, but to draw back from any philosophy that opens up the sceptical possibilities.

On this account, the way forward is to reject the picture of mind and body given to us by Cartesian dualism. And we should be encouraged to reject Cartesian dualism by metaphysical as well as epistemological pressures. Can we really get a possible picture of how the world is from Cartesian dualism, never mind about whether we know it is like that?

epiphenomenalism.)

John Locke

Gottfried Wilhelm Leibniz (1646–1716).

Actually Locke is not so far here from the doctrine known as occasionalism, which was embraced by another contemporary, Nicolas Malebranche (1638–1715). According to this, physical events do not strictly cause or bring about mental events at all. Rather, they provide the occasions upon which God himself inserts mental events of appropriate kinds into our biographies.

It is interesting that Leibniz uses a mathematical analogy. It is not just that he was an even better mathematician than Descartes, and amongst other things invented the calculus. It is rather that for Leibniz the whole order of nature must eventually be transparent to reason. When things fall out one way or another it is not just that they happen to do so. There must be, if we could only see far enough, a reason why they do. Things have to make sense. When Leibniz says God does nothing in an arbitrary or unprincipled way he is not really expressing a piece of theological optimism, so much as insisting that we ought to be able to see why things are one way or another. This is his ‘principle of sufficient reason’. In Descartes’s terms, we ought to be able to achieve a clear and distinct idea of why things fall out as they do. We should be able to gain insight into why the way things are is the way they must be. It is this confidence in what ought to be possible to reason that makes Leibniz, like Descartes, a ‘rationalist’.

In the philosophy of mind the Leibnizian must deny the possibility of Zombies and Mutants. If the physical biography is fixed, then the mental biography is fixed thereby. There is no independent variation, actual or possible. The philosophical problem is that of understanding why this is so. It is a question of how to understand the way in which the entire physical story makes true the mental story.

Today as well there are thinkers (sometimes called ‘new mysterians’) who think we shall never understand the relationship between mind and matter.

Analysis, as philosophers aim at it, attempts to say what makes true some mysterious kinds of statement, using terms from some less mysterious class.

Philosophers also talk of a reduction of statements of one kind to those of another. Analyses provide the reductions.

Analysis tells us what is meant by statements made in one form of words, in terms of statements made in other words.

The point is that if we can analyse mental ascriptions in physical terms, then the Leibnizian dream of a rational or a priori way of seeing how the physical gives rise to the mental is vindicated.

This doctrine is called logical behaviourism. I believe there is something right about it, but there are certainly difficulties.

Contemporary thinkers tend not to pin too much faith on behaviourism of this kind. They prefer a slightly more elaborate doctrine known as functionalism. This too pays prime attention to the function of the mental state. But it identifies that function in a slightly more relaxed way. It allows for a network of physical relationships: not only dispositions to behaviour, but typical causes, and even effects on other mental states—providing those in turn become suitably expressed in physical dispositions. But the idea is essentially similar.

It is possible to suggest that there is a middle route: one that opposes the happenstance, but does not go so far as a mathematical or rationally transparent relationship. This is usually put by saying that perhaps there is a metaphysical identity between mental and physical facts or events, but that it is not necessarily one that can be known a priori.

Once again, there would be a complete reduction of the mental to the physical. This would be what is called a psycho-physical identity theory.

This is the heart of the ‘anti-private-language’ argument in his Philosophical Investigations (published posthumously in 1953), one of the most celebrated arguments of twentieth-century philosophy. Wittgenstein tried to show that there could be no significant thought about the nature of one’s past (or future) mental life if that mental life is divorced from the physical world in the way that Cartesian dualism proposes. It becomes, as it were, too slippery or ghostly even to be an object of our own memories or intentions.

Probably the right reaction to this is to deny that thoughts are things at all. The mistake of supposing that to every noun there corresponds a ‘thing’ is sometimes called the mistake of reification.

Thinking is a matter of taking the world to be one way or another, and so taking it is a matter of our dispositions rather than a matter of what things are hanging out inside us.

We say that an intelligent system, such as a guided missile, thinks

Immediately, I'm anxious about using a technological system (defined narrowly) to illuminate human thought and behavior. Consider, obviously, that a guided missile doesn't "think" in any meaningful sense of the term at all.