Bertrand Russell, The Problems of Philosophy

Posted: Mon, Mar 30, 2026

Today

Pick up on our discussion: How do I know that I’m not in the Matrix, not in the Truman Show, not a dreaming butterfly, not a brain in a vat?
Russell’s strategy: Inference to the best explanation (IBE)
Announcement: Zine reading + launch party (April 11)

Russell: IBE offers us good reason for believing, even if it does not prove, that we are not in a skeptical scenario.

Observations: It hasn’t rained; the grass is wet.

Hypothesis I: It rained.
Hypothesis II: The sprinklers came on.
Hypothesis III: Grass does not get wet on its own without being rained on except at BC where laws of nature do not apply.
Hypothesis IV: Aliens visited BC to play water pistols.

Some theoretical virtues:

Explanatory power: How well does the hypothesis render the observations predictable/expectable?
Parsimony: How many principles and entities does the hypothesis postulate in order to do this? (“Ockham’s razor”)
Consistency: How well does the hypothesis avoid contradicting itself?
Unity: How well does the hypothesis avoid ad hoc elements that don’t integrate into a whole?
Conservatism: How well does the hypothesis cohere with already-established theories?

Observations: There appear to be tables, chairs, …

Russell: The real-world hypothesis should be preferred because it is more “simple” or less elaborate.