Die Leibniz-Handschriften der Königlichen Öffentlichen Bibliothek
Eduard Bodemann (ed)
p 56

Sämtliche schriften und briefe series VI volume 4
Deutsche Akademie der Wissenschaften (ed)
p 1474

Date: 1683 - 1685?

Translated from the Latin

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[BH p56] [A VI 4, p1474]

     I fear the opinion of the Cartesians will eventually be refuted by experience if men were to take greater pains in teaching animals. Descartes, writing to More, correctly asserts that he knows demonstratively that all the actions of beasts are able to be explained without invoking souls,1 so that the contrary cannot be demonstrated, but this needs to be understood according to metaphysical rigour, by which this cannot be demonstrated in relation to men.


1. 'there are two different principles causing our movements. The first is purely mechanical and corporeal, and depends solely on the force of the spirits and the structure of our organs, and can be called the corporeal soul. The other, an incorporeal principle, is the mind or that soul which I have defined as a thinking substance. Thereupon I investigated very carefully whether the movements of animals originated from both of these principles or from one only. I soon perceived clearly that they could all originate from the corporeal and mechanical principle, and I regarded it as certain and demonstrated that we cannot at all prove the presence of a thinking soul in animals.' Descartes, Letter to Henry More 5 February 1649 in John Cottingham, Robert Stoothoff, Dugald Murdoch & Anthony Kenny (eds), The Philosophical Works of Descartes Vol. III (Cambridge: Cambridge University Press, 1991), p365.

© Lloyd Strickland 2005
With gratitude to John Thorley for advice and suggestions