I hear that this has been tried before but it didn't really land because finding viable substitutes for particular terms can be difficult. I'm fascinated by language though and I wanted to take a shot at this myself.
Just a disclaimer that I'm not trying to drag anyone over using any of these terms and I'm not going to pretend that I'm some paragon of anti-ableism myself - I have work to do on this front, you probably do too and if we all work together we can make some positive change and establish better habits and a more supportive culture in our communities.
Here's a list of words that are more socially acceptable in their ableism and some suggestions for alternatives:
Crazy, Stupid, Dumb, Moronic, Idiotic
[In the sense that something is incorrect or bad]
Silly, foolish, absurd, ridiculous, laughable, nonsense/nonsensical, illogical, incomprehensible, inscrutable, irrational, contradictory, hypocritical, self-defeating, naive, ill-conceived, inane, asinine, counterproductive, unbelievable,
Crazy, Mad
[In the sense of letting loose or being enthusiastic]
Going wild, getting stuck into something, in a frenzy, on a rampage, being engrossed, head over heels, obsessed.
Psychotic, Psychopath, Psycho
[In the sense that something is cruel]
Vicious, bloodthirsty, monstrous, horrific, sadistic, heartless, brutal, ruthless, horrendous, reprehensible, despicable, depraved.
Crippled
Hamstrung, moribund, incapacitated, impaired, ineffective/ineffectual, hog-tied (lol).
What are some other ableist words that are pretty commonplace even amongst the left that you've heard?
Are there terms that I have overlooked or any ones that you use yourself that you'd like to replace?
Good question.
The easy answer is words like unintelligent, dense, oblivious, ignorant etc.
To answer the broader question though I think it's worth considering how you frame your understanding of something that you'd call stupid - we can use words that are euphemisms for ableist terms but that doesn't really address the underlying beliefs, sorta like how politicians will use racist dogwhistles like "gangs" and "inner-city crime" to make a statement that is essentially the same thing that would have been said 75 years ago with the only difference being that they aren't using the N-word. What happens in this situation is known as the euphemism treadmill where a new word slots into the gap left by the removal of an older slur and it gradually adopts the same qualities of the older slur because the usage of the word and the underlying beliefs remain the same.
So in that sense I personally try to think of terms that are more specific and more descriptive - a term like dumb is usually a catch-all term that can be applied virtually anywhere but often I find if I think about the way in which something is bad, I can use a more suitable alternative.
It's a bit like how the word "good" encompasses a whole lot of different positives depending on context: strong, healthy, agreeable, friendly, beautiful, delicious, durable, cost-effective, morally correct, clever etc.
You can't really insult someone by saying they're not intelligent enough without it being ableist. I still have a long way to go to improve my own vocabulary and root out some ableist brainworms, but the fundamental idea we all gotta grapple with is that there are enormous structural forces that have shaped the way we assess a human's worth. Those forces stem, in large part, from ableism and all other forms of bigotry. We should think long and hard about why we use certain words to disparage people (especially when we feel that they deserve it 100%) and how they reflect negative societal attitudes.
if we're recognizing that IQ is fake and "intelligence" is either also fake or so general as to be nearly meaningless as a one-dimensional measure, what are we even referring to if we're trying to be disparaging on that basis?
It's like race. Race is fake, there's no actual physical or biological reality backing it up. But because of the superstructure that surrounds those notions, there's arbitrary traits that a person has about them that determine what role they play in the system.
“You and I don’t agree”
That’s it. That’s what is being disparaged