“No,” says the philosopher. “It’s not a false dichotomy! For the sake of argument we’re suspending the laws of physics. Didn’t Galileo do the same when he banished friction from his thought experiment?” Yes, but a general rule of thumb emerges from the comparison: the utility of a thought experiment is inversely proportional to the size of its departures from reality.
IIRC, he says that in Intuition Pumps and Other Tools for Thinking.
You’re right. Thanks!