This is the crankiest comment I&#x27;ve seen on HN in a while. You &quot;know Fields medalists&quot;? Right.<p>You think that Pricipia Mathematica is the source of all truth in mathematics? Wrong. Most mathematicians working on foundational questions start out by learning Zermelo-Fraenkel set theory, which is well-understood, and avoids several difficulties that Russel had. While few people have read PM, it remains important because it goes through the hard task showing that high-level mathematics (calculus, &amp;c.) can have rigorous, first-principle proofs.<p>&quot;PM is like a compiler before there were compilers.&quot; What?<p>&quot;I asked a math professor about the &#x27;=&#x27; sign and how things can be equal at all (...)&quot; OMGWTFNO. I&#x27;ve seen comments like this before. Typically, it creates debate around a non-issue by sowing confusion and never nailing down precisely what we are talking about (hence the need for formal methods—it helps us call bullshit on comments like this).<p>&quot;Two things are equal iff their transformation leads to the origin. [A - B = 0]&quot;. Wrong. There are equality relations that do not require the existence of a zero or the concept of addition or subtraction.