The Philip Ball's Freedom to Think

Hobbes became convinced that this must be the axiom he was seeking. Constant motion was the natural state of all things - including people. All human sensations and emotions, he concluded, were the result of motion. From this basic principle Hobbes would work upwards to a theory of society.

What, precisely, does Hobbes mean by this assumption? It is, to modern eyes, a cold and soulless (not to mention an obscure) description of human nature. He pictured a person as a sophisticated mechanism acted upon by external forces. This machine consists of not only the body with its nerves, muscles and sense organs, but also the mind with its imagination, memory and reason. The mind is purely a kind of calculating machine - a computer, if you will. Such machines were popular in the seventeenth century: the Scottish mathematician John Napier (1550-1617) devised one, as did the French philosopher and mathematician Blaise Pascal (1623-62). They were mechanical devices for adding and subtracting numbers; and this, said Hobbes, is all the mind does too:

When a man Reasoneth, hee does nothing else but conceive a summe totall, from Addition of parcels; or conceive a Remainder, from Subtraction of one summe from another . . . For REASON . . . is nothing but Reckoning.

The body, meanwhile, is merely a system of jointed limbs moved by the strings and pulleys of muscles and nerves. Man is an automaton.

Indeed, Hobbes held that the ingenious mechanical automata created by some inventors of the era were truly possessed of a kind of primitive life. To him there was nothing mysterious or upsetting about such an idea. Others were less sanguine: the Spanish Inquisition imprisoned some makers of automata on the grounds that they were dabbling in witchcraft and black magic.

What impelled Hobbes's mechanical people into action was not just external stimuli relayed to the brain by the apparatus of the senses. They were imbued also with an inner compulsion to remain in motion. For what is death but immobility, and which person did not seek to avoid death? 'Every man . . .', said Hobbes, 'shuns . . . death, and this he doth, by a certain impulsion of nature, no less than that whereby a stone moves downward.'

Mankind's volitions, therefore, are divided by Hobbes into 'appetites' and 'aversions': the desire to seek ways of continuing this motion and to avoid things that obstruct them. Some appetites are innate, such as hunger; others are learnt through experience. To decide on a course of action, we weigh up the relevant appetites and aversions and act accordingly.

What Hobbes means by 'motion' is a little vague, for he clearly does not intend to imply that we are forever seeking to run around at full pelt. Motion is rather a kind of liberty - a freedom to move at will. Those things that impede liberty impede motion. Even if a man sits still, the mechanism of his mind may be in furious motion: the freedom to think is an innate desire too.

What room is there in this mechanical description for free will? According to Hobbes, there is none - he was a strict determinist. Humans are puppets whose strings are pulled by the forces at play in the world. Yet Hobbes saw nothing intolerable in this bleak picture. After all, he believed that he had arrived at this basic, indisputable postulate about human nature by introspection - by considering his own nature. The first puppet he saw was himself:

whosoever looketh into himself, and considereth what he doth, when he does think, opine, reason, hope, feare, &c, and upon what grounds; he shall thereby read and know, what are the thoughts, and Passions of all other men, upon the like occasions.


Critical Mass: How One Thing Leads to Another

by Philip Ball

Winner of Aventis Prize, the world's most prestigious Science book award