Descartes: A Biography

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The ScientificEssaysand theDiscourse on Method 

There are two other general qualifications of the nature of this project,

both of which were to give rise to serious discussions and critiques in the

following years. One was that Descartes had to present his results in a

hypothetical manner because the general principles of physics, on which

the explanations relied, could not be divulged yet.

It is true that, since knowledge of these things depends on general principles of nature

that have not yet been well explained, as far as I know, I have to use some assumptions

atthe beginning, as I did in theDioptrics.However,Ishall try to make them so simple

and easy that, perhaps, you will have no difficulty in believing them, even though I

have not yet demonstrated them. (vi.)

This refers to the three laws of nature and the general assumptions that

had been presented inThe World,onwhich most of the explanations in

theMeteorsrelied. The effects of this self-imposed limitation become evi-

dent, for example, in the explanation of winds in the fourth discourse.

Had he been able to refer to the daily revolution of the Earth, he might

have explained more readily the movement of air around the Earth ‘from

east to west’. As long as he had to remain silent about that sensitive topic,

he could only invite readers to accept that assumption, because its expla-

nation ‘cannot easily be deduced without explaining the whole fabric of

the universe, something that I have no intention of doing here’ (vi.).

The other caveat had similar connotations of the earlier unpublished

work. Descartes was very conscious of the extent to which he was replacing

traditional scholastic explanations of natural phenomena, which relied on

what were called ‘qualities’ and ‘forms’. In place of the multiplicity of such

exotic entities, he asked his readers to accept that there was only one matter

in the universe, that it was divisible into indefinitely small parts, and that

all the natural phenomena mentioned in this treatise could be explained by

reference to the size, shape, disposition, and movement of parts of matter.

He could obviously anticipate the reaction of his learned contemporaries

in the universities, and he lamely tried to avoid controversy by suggesting

that he was not arguing against their theories but merely proposing an

alternative, simpler theory.

Finally, you should know that, to avoid breaking the peace with philosophers, I do not

atall wish to deny anything they imagine in bodies over and above what I have talked

about, such as their ‘substantial forms’, their ‘real qualities’, and similar things, but it

seems to me that my explanations should be approved to the extent that I make them

depend on fewer things. (vi.)