I was listening to an episode of the Rationally Speaking podcast, which overall is quite good, but from time to time I disagree. In this case they were talking about the technical use of terms versus the colloquial use. We see that in physics a lot, with terms like energy, force, and heat, and one has to be very careful when using these terms. In the podcast, they used the example of people using the word “logical”, as in “that is the logical thing to do”. The host thought this should really mean “that is the reasonable thing to do”, given that they aren’t generally doing a deductive proof to make the decision. The tone he used was that this should be obvious…however it is not…it is wrong. Why should the word “logical” be restricted to deductive logic? Why should it not include inductive logic? Pretty much that pulls in all of probability theory, and it then becomes (nearly) synonymous with “reasonable”.
When I say the two phrases in my head, I do sense a subtle differerence, with “logical” being more definititive than “reasonable”. Perhaps it is more of a difference like “probable” and “plausible” – still not a deductive distinction, but a distinction of magnitude in inductive reasoning.
Still, it is an interesting thing to think about how we use language in science and society.