Descartes' canine experiment

Pavlov's experiment with a dog to demonstrate classical conditioning is well known, but a letter uncovered by Oxford University’s Electronic Enlightenment project suggests that Descartes devised a thought experiment using the same animal 300 years earlier.

In a letter to his friend Marin Mersenne on 18 March 1630, the French philosopher wrote: 'I reckon that if you whipped a dog five or six times to the sound of a violin, it would begin to howl and run away again.'

The letter explained: 'What makes some people want to dance many make others want to cry. This is because it evokes ideas in our memory: for instance those who have in the past enjoyed dancing to a certain tune feel a fresh wish to dance the moment they hear a similar one; on the other hand, if someone had never heard a galliard without some affliction befalling him, he would certainly grow sad when he heard it again.'

Dr Robert McNamee, director of Electronic Enlightenment, says: ‘It is striking just how similar Descartes' theory on 'reflex' is to Pavlov’s theory of ‘conditioning. Just as in Pavlov’s conditioning experiment, performed 271 years after Descartes' letter, the two stimuli necessary for conditioning, the conditioned and unconditioned stimuli, are paired causing the planned conditional response.

'In Descartes’ letter, the planned conditional response is fear. In Pavlov’s experiments, the planned conditional response is the saliva elicited by hunger. For all animal lovers it is fortunate that Descartes' experiment remained a theory, discussed in letters to friends, while Pavlov carried out the conditioning experiment in practice.

He adds: 'Moreover in both examples, the conditioned stimulus linked to sound – a violin and a bell cause the planned conditional response.'

It is well known in the history of psychology that Descartes was an early thinker of classical conditioning, which he referred to as 'reflex', so this letter does not change what we know about Descartes. But taken as a whole Dr McNamee says the corpus of letters to and from Descartes which are held in the Electronic Enlightenment database provides nuance and depth of structure to our narrative of the history of psychology and of Descartes’ philosophy.

Dr McNamee came across the letter by searching the database of the Electronic Enlightenment website, which holds more than 60,000 letters between more than 7,400 correspondents in the early modern period.  More information is available on the website.

Top image: Lily the dog, by Sam Pickles (www.flickr.com/retroninja007); Bottom image: Portrait of Descartes by Frans Hals (wikimedia commons)