6 Comments
User's avatar
Scott's avatar

Good observation. Taleb talked about black swans, but he didn't emphasize that they're mostly bad guys.

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Scott's avatar

On reflection, he did and I missed it; he called them swans. ;-)

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Isaac King's avatar

I think it's important to note that this is not actually a criticism of Bayesian decision theory (or evidential decision theory, as Wikipedia calls it), but rather a criticism of *improperly performed* Bayesian decision theory. When the agent correctly accounts for all possibilities they're aware of and assigns them the appropriate epistemic probabilities, this problem doesn't exist.

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Philosophy bear's avatar

No I'd say it's more fundamental than that, at least potentially. Bayesian decision theory relies conceptually on the assumption that the agent is aware of all possibilities. The question "what should you do about possibilities you're unaware of" is a nonsense question in a strict classical Bayesian decision theoretic framework. There are extensions of the framework to deal with this, e.g. See Steele and Stefansson's book: https://katiesteelephilosophy.weebly.com/

But within the basic framework itself- the there's no answer. This is not just a practical problem, it's a problem reflected in the conceptual foundations.

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Isaac King's avatar

Why isn't this handled by the "everything else" possibility?

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Philosophy bear's avatar

An "anything else" possibility can help, but it's an add on- at least seemingly- to the conceptual machinery- a kludge of sorts.

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