Single Idea 5401

[catalogued under 4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic]

Full Idea

We would do better to go straight from the evidence that some men have died to the mortality of Socrates, than to go via 'all men are mortal', for the probability that Socrates is mortal is greater than the probability that all men are mortal.

Gist of Idea

The mortality of Socrates is more certain from induction than it is from deduction

Source

Bertrand Russell (Problems of Philosophy [1912], Ch. 7)

Book Reference

Russell,Bertrand: 'The Problems of Philosophy' [OUP 1995], p.45


A Reaction

Russell claims that deduction should stick to a priori truth, and induction is best for the real world. Interesting. To show that something is a member of a set (e.g. planets) you need an awful lot of knowledge of the set.