INSCITIA:
Is 'and' definable in formal logic? More generally, are any of the basic logical operations definable in formal logic? 'And' is symbolized with a floating dot, namely, •. "I am tall and I am short" is symbolized as "p • q". "I am short" can be symbolized as M ∃ P(x), where M ∃ means "there is a man" and P(x) means "it is true that x is tall". "I am not short" would be ¬M ∃ P(x), etc ("there is no man such that…).
But can we state 'and' in formal notation? And has a meaning, so can't it be stated as a sort of proposition? Would it be • ≡ • ∀ P(x) ∪ x ∍ (p ∨ q ∌ ¬p ∨ ¬q)?
I am way too weak in formal logic to crack this right now. But in normal English I am inclined to say "'and' is materially equivalent to all cases where x is a member of the set that contains [the attributes or propositions] p, q, no negation of p, and no negation of q (as well as any further elements that can be listed with p)." But then we've used and in the definition. Well?
RESPONSUM:
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ADDENDUM:
Description : Symbol
Disjunction :
Material implication :
Material equivalence :
Negation of material equivalence :
Negation of equality :
Therefore :
Semantic consequence :
Syntactic consequence :
Existential quantifier :
Universal quantifier :
Set membership :
Denial of set membership :
Set intersection :
Set union :
Subset :
Proper subset :
One-to-one correspondence :
Aleph :
Gamma :
Delta :
Necessity :
Possibility :