THE MATERIAL WORLD - DESCARTES

« Descartes' Meditations brought him fame throughout Europe.

He entered into correspondence and controversy with most of the learned men of his time, especially through the intermediary of a learned Franciscan, Marin Mersenne.

Some of his friends began to teach his views in universities; and in the Principles of Philosophy he set out his metaphysics and his physics in the form of a textbook.

Other professors, seeing their Aristotelian system threatened, subjected the new doctrines to violent attack.

However, Descartes did not lack powerful friends and so he was never in real danger. One of his correspondents was Princess Elizabeth of the Palatine, the niece of King Charles I of England.

She presented a number of shrewd objections to Descartes' account of the interaction of mind and body, to which he was unable to give a satisfactory answer.

Out of their correspondence grew the last of his fulllength works, the Passions of the Soul.

When it was published, however, this book was dedicated not to Elizabeth but to another royal lady who had interested herself in philosophy, Queen Christina of Sweden.

Against his better judgement Descartes was persuaded to accept appointment as court philosopher to Queen Christina, who sent an admiral with a battleship to fetch him from Holland.

The Queen insisted on being given her philosophy lessons at 5 o'clock in the morning.

Under this regime Descartes, a lifelong late riser, fell victim to the rigours of a Swedish winter and died in 1650. Some of the most important of Descartes' doctrines were not fully spelt out in his published works, and only became clear when his voluminous correspondence was published after his death.

One such is his doctrine of the creation of the eternal truths; another is the theory that animals are unconscious automata. In 1630 Descartes wrote to Mersenne: The mathematical truths which you call eternal have been laid down by God and depend on Him entirely no less than the rest of his creatures.

Indeed to say that these truths are independent of God is to talk of Him as if He were Jupiter or Saturn and to subject him to the Styx and the Fates.

Please do not hesitate to assert and proclaim everywhere that it is God who has laid down these laws in nature just as a king lays down laws in his kingdom.

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It will be said that if God had established these truths He could change them as a king changes his laws.

To this the answer is ‘Yes he can, if His will can change'.

‘But I understand them to be eternal and unchangeable' – ‘I make the same judgment about God' ‘But His will is free.' – ‘Yes, but His power is incomprehensible.' It was an innovation to make the truths of logic and mathematics depend on God's will.

It was not that previous philosophers thought such truths were totally independent of God; according to most thinkers, they were independent of God's will, but dependent upon, indeed in some sense identified with, his essence.

Descartes was the first to make the world of mathematics a separate creature, dependent, like the physical world, upon God's sovereign will. This doctrine, Descartes said, was the necessary foundation of his physical theory.

He rejected, systematically, the Aristotelian apparatus of real qualities and substantial forms, both of which he regarded as chimerical entities.

The essences of things, he maintained, are not forms as conceived by Aristotle; they are simply the eternal truths, which include the law of inertia and other laws of motion as well as the truths of logic and mathematics.

Now in the Aristotelian system it was the forms and essences that provided the element of stability in the flux of phenomena which made it possible for there to be universally valid scientific knowledge.

Having rejected essences and forms, Descartes needed a new foundation for the certain and immutable physics that he wished to establish.

If there are no substantial forms, what connects one moment of a thing's history to another? Descartes' answer is: nothing but the immutable will of God.

And to reassure ourselves that the laws of nature will not at some point change, we have once again to appeal to the veracity of God, who would be a deceiver if he let our inductions go astray. In Descartes' system we have a world of physics governed by deterministic laws of nature, and we have the mental world of the solitary consciousness.

Human beings, as compounds of mind and body, straddle both worlds uncomfortably.

Where do non-human animals fit in? According to most thinkers before Descartes, animals differ from human beings by lacking rationality, but resemble them in possessing the capacity for sensation.

But Descartes' account of the nature of sensation makes it difficult to attribute it to animals in the same sense as we attribute it to human beings.

In a human, according to Descartes, there are two elements in sensation: on the one hand, there is a thought (e.g.

a pain, or an experience as it were of seeing a light), and on the other hand, there are the mechanical motions in the body which give rise to that thought.

The same mechanical motions may occur in the body of an animal as occur in the body of a human, and if we like we can, in a broad sense, call these sensations; but an animal cannot have a thought, and it is thought in which sensation, strictly so called, consists.

It follows that, for Descartes, an animal cannot have a pain, though the machine of its body may cause it to react in a way which, in a human, would be the expression of a pain.

As Descartes wrote to an English nobleman: I see no argument for animals having thoughts except the fact that since they have eyes, ears, tongues, and other sense-organs like ours, it seems likely that they have sensations like us; and since thought is included in our mode of sensation, similar thought seems to be attributable to them.

This argument, which is very obvious, has taken possession of the minds of all men from their earliest age.

But there are other arguments, stronger and more numerous, but not so obvious to everyone, which strongly urge the opposite. This doctrine did not seem quite as shocking to Descartes' contemporaries as it does to most people nowadays; but they reacted with horror when some of his disciples claimed that human beings, no less than animals, were only complicated machines. Descartes' two great principles – that man is a thinking substance, and that matter is extension in motion – are radically misconceived.

In his own lifetime phenomena were discovered which were incapable of straightforward explanation in terms of matter in motion.

The circulation of the blood and the action of the heart, as discovered by the English physician William Harvey, demanded the operation of forces such as elasticity for which there was no room in Descartes' system.

None the less, his scientific account of the origin and nature of the world was fashionable for a century or so after his death; and for a while other, more fruitful, scientific conceptions of nature felt obliged to define their position in relation to his. Descartes' view of the nature of mind endured much longer than his view of matter: indeed, throughout the West, it is still the most widespread view of mind among educated people who are not professional philosophers.

As we shall see, it was later to be subjected to searching criticism by Kant, and was decisively refuted in the twentieth century by Wittgenstein, who showed that even when we think our most private and spiritual thoughts we are employing the medium of a language which cannot be severed from its public and bodily expression.

The Cartesian dichotomy of mind and matter is, in the last analysis, untenable.

But once grasped, its influence can never wholly be shaken off. More than any other philosopher, Descartes stands out as a solitary original genius, creating from his own head a system of thought to dominate his intellectual world.

It is true that there is hardly a philosophical argument in his works which does not make its appearance, somewhere or other, in the writings of earlier philosophers whom he had not read.

But no one else ever displayed the ability to combine such thoughts into a single integrated system, and offer them to the general reader in texts which can be read in an afternoon, but which provide material for meditation over decades.. »