Comment by seanhunter
1 month ago
Pretty sure Fermat didn’t have a proof.
For one thing, Fermat wasn’t actually a “professional” mathematician. He was a lawyer and judge and was known for having remarkable intuition but not really troubling himself too much with details of proofs etc. For example Descartes famously called him a “deficient mathematician”[1] in an angry exchange of letters over a technique that Fermat had discovered to geometrically construct a tangent to a particularly problematic curve called Descartes’ Folia using a technique we would now recognise as being the definition of the derivative as the limit of the difference quotient.
[1] Explained entertainingly here https://youtu.be/xKfEmbWBgvM?is=qLnPvPXGDqgJCDC3
Many accomplished mathematicians were not professional mathematicians. Surprisingly enough, many were in fact lawyers.
Descartes was himself a lawyer (by training) then there were Leibnitz, Cayley, Viete. If you include Physics you will get a bigger list.
Descartes and Fermat ran a mutual admiration society, don't read to much into it.
Both had independently come up with coordinate geometry, linking algebra and geometry
I agree Fermat probably had a wrong proof but curb your condescension towards lawyers making contributions in mathematics.
You misunderstand. I have a tremendous respect for Fermat. I just meant he didn’t feel compelled to be totally rigorous. There are examples of contemporaries complaining about him skipping steps and hand waving etc. That was just how he did things.
Agreed. Modern rigour is, well, quite modern.