On 2/14/2019 11:59 AM, Helmut Raulien wrote:
So far I think, that the sheet of assertion means to symbolize a
universe with clear true/false rules. But what, if every subject
(at least, if the subjects are organisms) has its own universe
(speaking with Uexküll and the constructivists)?
I'm now writing a longer note that will clarify the various issues.
But the Sheet of Assertion (SA) deserves a few more comments:
1. De Morgan introduced the term 'Universe of Discourse' (UoD) for
the totality of everything that is being discussed. He considered
the option of having different UoDs for different discussions.
2. Peirce adopted and broadened De Morgan's term. For EGs, he used
the SA for any topic that is under discussion, and he considered
the option of having multiple SAs for different contexts and
even different universes.
3. For modal logic, he generalized the idea to a pad of sheets, which
could represent different contexts or different possible worlds.
Whatever appears on one sheet is true for that possible world.
Whatever is necessarily true would appear on every sheet.
For Peirce's clearest and simplest tutorial about EGs (1909), see
http://jfsowa.com/peirce/ms514.htm .
In 1911, he sent a clean copy of MS 514 in a letter to Mr. Kehler,
a member of Lady Welby's Significs group. Since Peirce had a high
regard for Lady Welby and her colleagues, his choice of this version
shows that it was his preferred tutorial introducing EGs.
For more about Peirce's universes and their implications, see
http://jfsowa.com/pubs/5qelogic.pdf
John
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