Full Idea
In any possible world we feel that two and two would be four.
Gist of Idea
In any possible world we feel that two and two would be four
Source
Bertrand Russell (Problems of Philosophy [1912], Ch. 7)
Book Reference
Russell,Bertrand: 'The Problems of Philosophy' [OUP 1995], p.43
A Reaction
Thinking of necessity in terms of possible worlds is not a new invention, but then Russell was a keen fan of Leibniz. Suppose there were no world at all, and only one truth, namely that two and two make five? (No, I can't make sense of that!)