Peter

Feynman - if you're doing science, then [...]

*nods* Yes, I had that thought shortly after hitting send. Perhaps if you're approaching the analogy problem with the mind of an experimental physicist, you treat the premise abc → abd as an experimental observation, and the question becomes, 'Given that observation, what law of nature is most likely?' And then you take the Occam's Razor approach, and pick the simplest one that fits the observations – until, of course, further experimental results are obtained and the explanations that are too simple begin to be ruled out.

Perhaps Feynman's position, though on the surface it had what Hofstadter called a 'village idiot' nature about it (a curious contrast to your characterisation as 'smart aleck'!), would have revealed huge depths of subtlety had Hofstadter only thought to add one or two more exemplars to his analogy problems: 'If abc → abd and also def → deg, what does this or that go to? Do your answers change if it is later revealed that abd → abc? Or dba → cba?'