Journal for the History of Analytical Philosophy 2019-01-19T14:45:29-05:00 Marcus Rossberg Open Journal Systems <p>JHAP aims to promote research in and discussion of the history of analytical philosophy. <a href="/jhap/about">Read more ...</a></p> On the Curious Calculi of Wittgenstein and Spencer Brown 2019-01-19T14:45:29-05:00 Gregory Landini <p>In his <em>Tractatus</em>, Wittgenstein sets out what he calls his N-operator notation which can be used to calculate whether an expression is a tautology. In his <em>Laws of Form</em>, George Spencer Brown offers what he calls a “primary algebra” for such calculation. Both systems are perplexing. But comparing two blurry images can reduce noise, producing a focus. This paper reveals that Spencer Brown independently rediscovered the quantifier-free part of the N-operator calculus. The comparison sheds a flood light on each and from the letters of correspondence we shall find that Russell, as one might have surmised, was a catalyst for both.</p> 2018-12-09T10:05:46-05:00 ##submission.copyrightStatement##