When someone utters the phrase, "The brain is of course just a computer"
This tells you two things:
1. This person doesn't actually know that much about the brain/body/consciousness/etc.
2. You might also want to be suspicious about this person's thoughts on how computers work, too
All analogies break down at a certain point
All of them
They're all simplifications or extrapolations that are meant to make a point or emphasize something
And so when someone says "X is like Y"
You should figure out 1. what point they're trying to make with the analogy, 2. whether it actually is similar in those respects, and 3. where the analogy breaks down, and whether this is a problem for the argument at hand
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The Doctor