[gwern]

> But if people can live missing massive chunks of their brain, is it really believable that tiny differences can cause such massive societal outcomes?

Congratulations, you are today's demonstration of 'proving too much': you have also just proven that things like lesions and scars cannot affect cognition, warp personalities, create agnosias and aphasias, and result in bizarre conditions like those Oliver Sacks has so memorably documented, because lesions're so tiny and such small parts of the brain - 'if people can live missing massive chunks of their brain, is it really believable that tiny differences can cause such massive societal outcomes?'

[caseydurfee]

The OP was not talking about the magnitude of the differences, but the nature of them.

Do you believe that neuroplasticity remains constant throughout a person's lifetime? Unless you believe that, your statement is incoherent.

Lesions and scars are acute changes in the brain that happen after birth. That's different from starting out missing massive chunk of your brain.

OP: "Look at that person who was born with no arms due to a birth defect. They're able to live a fairly normal, happy life. Maybe arms aren't essential to human happiness."

You: "So you're saying if you got your hand mutilated in a garbage disposal, that wouldn't make you unhappy? A hand is much less than a whole arm."

(I'll leave what this makes you a demonstration of as an exercise for the reader.)

[gwern]

> The OP was not talking about the magnitude of the differences, but the nature of them.

And what, pray tell, are the 'nature' of disorders like Cotard's syndrome?

> OP: "Look at that person who was born with no arms due to a birth defect. They're able to live a fairly normal, happy life. Maybe arms aren't essential to human happiness."

Try going back and reading what was said. Your paraphrase is incorrect. Here's a correct paraphrase:

"OP: look at that person born with no legs. They're able to lead a somewhat normal life. This shows that anyone claiming that there might be differences between the fingered and the fingerless such as in fine motor control is a moron - because a leg is so much larger than a finger!"

> I'll leave what this makes you a demonstration of as an exercise for the reader.

Well, it demonstrates you can't paraphrase or follow the logical structure of an argument. I'm not sure what I'm demonstrating; hopefully something good.