The Metaphorical Fallacy
Consider the following argument:
1. Cars are mechanical horses.
2. Horses are faster than walking.
3. Therefore, cars are faster than walking.
Pretty plausible, right? Unfortunately, this argument is logically as awful as:
1. Cars are mechanical horses.
2. Horses eat oats.
3. Therefore, cars eat oats.
Both arguments are examples of what I call the Metaphorical Fallacy. Its general form:
1. X is metaphorically Y.
2. Y is literally Z.
3. Therefore, X is literally Z.
Ludicrous, but oh so tempting – especially if you’re part of a subculture that loves the metaphor in question.
To take a not-so-random example, consider my dear friend and colleague, Robin Hanson. He’s a long-time member of the science fiction and AI subcultures. People in these subcultures love the metaphor, “The mind is a computer.” The result: For all his brilliance, Robin says many crazy things about the mind. Things like:
1. The human mind is a computer.
2. Computers’ data can be uploaded to another computer.
3. Therefore, the human mind can be uploaded to a computer.
I say this argument is just as ridiculous as:
1. The human mind is a computer.
2. A computer will overheat if its fan breaks.
3. Therefore, the human mind will overheat if its fan breaks.
The last time I checked, human minds don’t even have fans!
Maybe one day Robin’s conclusion will be vindicated. Maybe one day he’ll upload his mind to a computer. Though I seriously doubt it, I don’t deny the possibility. My objection isn’t to Robin’s conclusion, but to his argument. Calling the mind a computer is just a metaphor – and using metaphors to infer literal truths about the world is a fallacy.
P.S. I was vain enough to hope that I had discovered the Metaphorical Fallacy, but at least two philosophers already beat me to the punch.
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