'more stupid' vs 'stupider'

[MarenmjMakesBigPies]

which is the correct comparative?

I say it must be more stupid, but I keep seeing 'stupider' in official-looking context, and the dictionary lists them both!

Please tell me I am right. The pedant in me deepy desires to be able to look down on the populace for their mistakes.

[prism]

There's nothing wrong with "stupider" but "stupid", unlike most adjectives, sounds a bit like a past participle (steeped, etc) so to add "er" at the end feels wrong. You'd be even more unlikely to want to say "vapider", though I can't see any reason technically why you couldn't- it would just sound weird.

[mathanxiety]

I think the rule is that if an adjective has two or more syllables, then you say 'more' and the unchanged adjective.

'Lighter', 'smaller', 'rounder'... but then there's 'heavier'...

'More stupid', 'more graceful', 'more serendipitous', 'more generous'... but then there's 'more bored'. hmmm

Maybe the exceptions prove the rule. I would say 'more stupid'.

[MarenmjMakesBigPies]

Thanks :)

I prefer 'more stupid' too, but that may be, as prism says, because it just sounds nicer.

[mathanxiety]

It sounds less stupid.