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tut comments on How to Convince Me That 2 + 2 = 3 - Less Wrong

53 Post author: Eliezer_Yudkowsky 27 September 2007 11:00PM

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Comment author: tut 15 July 2009 01:41:11PM *  4 points [-]

I'm suspicious of claims that supposedly do not require justification

Mathematical claims do require justification. They even require stronger justification than empirical claims: mathematical proof. As Doug S explained, the proof that 2+2=4 is

2+2 = 2+(1+1) = (2+1)+1 = 3+1 = 4 QED.

(Using the definition of 2, the associativity of +, the definition of 3 and the definition of 4 in that order).

Empirical claims, such as "2+2=4 is related to earplugs or apples" do not require proofs, but they do require evidence.