Cf: Peirce’s 1870 “Logic of Relatives” • Comment 11.24
https://inquiryintoinquiry.com/2014/06/08/peirces-1870-logic-of-relatives-c…
Peirce’s 1870 “Logic of Relatives” • Comment 11.24
https://oeis.org/wiki/Peirce%27s_1870_Logic_Of_Relatives_%E2%80%A2_Part_2#C…
Note. Please see the blog post linked above for the proper formatting,
as some of what's discussed below depends on the typography in various
editions and transcriptions of Peirce's text.
All,
We come to the last of Peirce's observations
about the “number of” function from CP 3.76.
NOF 4.4
=======
<QUOTE CSP:>
It is to be observed that
• [\mathit{1}] = 1.
Boole was the first to show this connection between
logic and probabilities. He was restricted, however,
to absolute terms. I do not remember having seen any
extension of probability to relatives, except the
ordinary theory of “expectation”.
Our logical multiplication, then, satisfies the essential
conditions of multiplication, has a unity, has a conception
similar to that of admitted multiplications, and contains
numerical multiplication as a case under it.
(Peirce, CP 3.76 and CE 2, 376)
https://inquiryintoinquiry.com/2014/04/29/peirces-1870-logic-of-relatives-s…
</QUOTE>
There are problems with the printing of the text at this point.
To recall the conventions we are using in this transcription,
\mathit{1} is the italic 1 denoting the dyadic identity relation
\mathfrak{1} is the “antique figure one” which Peirce defines
as 1_∞ = “something”.
Collected Papers CP 3 gives [\mathit{1}] = \mathfrak{1}, which does not make sense.
Chronological Edition CE 2 gives the 1's in different styles of italics but reading
the equation as [\mathit{1}] = 1 makes better sense if the latter “1” is the numeral
denoting the natural number 1 and not the absolute term “1” denoting the universe of
discourse. The quantity [\mathit{1}] is defined as the average number of things
related by the identity relation \mathit{1} to one individual, and so it makes sense
that [\mathit{1}] = 1 in N, where N is the set of non-negative integers {0, 1, 2, …}.
With respect to the relative term \mathit{1} in the syntactic domain S
and the number 1 in the non-negative integers N we have the following.
• v(\mathit{1}) = [\mathit{1}] = 1.
At long last, then, the “number of” mapping v : S → R
has another one of the properties required of an arrow
from logical terms in S to real numbers in R.
Regards,
Jon