"John F. Sowa" <s...@bestweb.net>
wrote:
Jon, List,
I have a high regard for the work that Ahti and Francesco have been doing, and I read the article you cited (copy of the reference below). They have been doing meticulous scholarship on the development of Peirce's EGs up to 1911. But unfortunately, they overlooked the implications of those five MSS from 1911.
While Peirce was writing the three EG rules of inference around 8 pm on 2 June 1911, he suddenly realized that the rules depend *only* on whether an area is positive or negative. There is nothing special about a scroll.
To see the difference, do a detailed comparison of R669 and R670. After June 2, everything depends on whether an area is shaded or unshaded. In R670, the primitives are existence, conjunction, and negation, The scroll is just a convenient way to draw two ovals without raising the pen.
There is much more to say, but I'm short on time.
John
---------------
JAS> I have been thinking about writing an article on this topic myself, but it turns out that Bellucci and Pietarinen already covered a lot of the relevant ground in a 2016 paper (https://www.researchgate.net/publication/275038453_Existential_Graphs_as_an_Instrument_of_Logical_Analysis_Part_1_Alpha). Here are a few especially pertinent excerpts, which are entirely consistent with what I have been advocating all along.
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