Speranza
I read at
http://www.realfunnyjokes.com/archives/msg142.html
Always remember you're unique, just like everyone else.
I guess there must be a way (an easy one, even) to symbolise that, in first-order predicate logic, so that we get the symbolic humour out of it?
Cheers.
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This sounds something like Leibniz's identity of indiscernibles, except that it has a completely trivial version which I understand Leibniz's principle is not.
ReplyDeleteThe trivial version is:
forall x and forall y not equal to x, x is distinct from y
Or in plain(er?) English, everyone is unique, because everyone else is someone else.
Roger
Indeed.
ReplyDeleteIt may also connect with
'haecceity', which, as I read from Wikipedia,
is
"from the Latin haecceitas, which translates as "thisness")"
"a term from medieval philosophy first coined by Duns Scotus which denotes the discrete qualities, properties or characteristics of a thing which make it a particular [shall we say, 'unique'? -- Speranza] thing.
"Haecceity is a person or object's "thisness", the individualising difference between the concept 'a man' and the concept 'Socrates' (a specific person)."
Incidentally, Wikipedia provides two formalisations of the Leibniz claim:
http://en.wikipedia.org/wiki/Identity_of_indiscernibles
The indiscernibility of identicals
For any x and y, if x is identical to y, then x and y have all the same
properties.
∀x∀y[x = y --> ∀P(Px <--> Py)]
The identity of indiscernibles
For any x and y, if x and y have all the same properties, then x is
identical to y.
∀x∀y[∀P(Px <--> Py) --> x = y]
Finally, it connects with the iota operator, as one reads from
http://web.gc.cuny.edu/philosophy/faculty/neale/papers/LudlowNeale.pdf
since 'uniqueness' is such an important claim in Russell's (and indeed Grice's) analysis of "The king of France is (or is not) bald" -- _contra_ Strawson, of course.
"For Russell, descriptions are ‘incomplete’ symbols, they have ‘no
meaning in isolation’, they do not
stand for things. In Principia Mathematica (PM), a description is
represented by a quasi-singular term of
the form
(ιx)φx
-- which can be read as:
‘the UNIQUE x which is φ.’
Superficially, the iota-operator, (ιx), is a
variable-binding device for forming a singular term from a formula φx. A
predicate symbol ψ may be prefixed
to a description (ιx)φx to form a formula ψ(ιx)φx, which can be expanded
in accordance with a
suitable contextual definition. (To define an expression ζ contextually is
to provide a procedure for
converting any sentence containing occurrences of ζ into an equivalent
sentence that is ζ-free."