structure for 'Theory of Logic'    |     alphabetical list of themes    |     unexpand these ideas

5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / d. and

[role of 'and' in systems of logic]

7 ideas
'Are Coriscus and Callias at home?' sounds like a single question, but it isn't [Aristotle]
     Full Idea: If you ask 'Are Coriscus and Callias at home or not at home?', whether they are both at home or not there, the number of propositions is more than one. For if the answer is true, it does not follow that the question is a single one.
     From: Aristotle (Sophistical Refutations [c.331 BCE], 176a08)
     A reaction: [compressed] Aristotle is saying that some questions should not receive a 'yes' or 'no' answer, because they are equivocal. Arthur Prior cites this passage, on 'and'. Ordinary use of 'and' need not be the logical use of 'and'.
Combining two distinct assertions does not necessarily lead to a single 'complex proposition' [Mill]
     Full Idea: In 'Caesar is dead, and Brutus is alive' ...there are here two distinct assertions; and we might as well call a street a complex house, as these two propositions a complex proposition.
     From: John Stuart Mill (System of Logic [1843], 1.04.3)
     A reaction: Arthur Prior, in his article on 'tonk', cites this to claim that the mere account of the and-introduction rule does not guarantee the existence of any conjunctive proposition that can result from it. Mill says you are adding a third proposition.
Saying 'and' has meaning is just saying it works in a sentence [Wittgenstein]
     Full Idea: When we say that the word 'and' has meaning what we mean is that it works in a sentence and is not just a flourish.
     From: Ludwig Wittgenstein (Lectures 1930-32 (student notes) [1931], B VIII.2)
I might accept P and Q as likely, but reject P-and-Q as unlikely [Harman]
     Full Idea: Principles of implication imply there is not a purely probabilistic rule of acceptance for belief. Otherwise one might accept P and Q, without accepting their conjunction, if the conjuncts have a high probability, but the conjunction doesn't.
     From: Gilbert Harman ((Nonsolipsistic) Conceptual Role Semantics [1987], 12.2.2)
     A reaction: [Idea from Scott Soames] I am told that my friend A has just won a very big lottery prize, and am then told that my friend B has also won a very big lottery prize. The conjunction seems less believable; I begin to suspect a conspiracy.
A truth-table, not inferential role, defines 'and' [Fodor]
     Full Idea: I'm inclined to think that 'and' is defined by its truth-table (and not, for example, by its 'inferential-role').
     From: Jerry A. Fodor (LOT 2 [2008], Ch.7)
     A reaction: Sounds right, on my general principle that something can only have a function if it has an intrinsic nature. The truth-table just formalises normal understanding of 'and', according to what it makes true.
Is the meaning of 'and' given by its truth table, or by its introduction and elimination rules? [Forbes,G]
     Full Idea: The typical semantic account of validity for propositional connectives like 'and' presupposes that meaning is given by truth-tables. On the natural deduction view, the meaning of 'and' is given by its introduction and elimination rules.
     From: Graeme Forbes (The Metaphysics of Modality [1985], 4.4)
The connective 'and' can have an order-sensitive meaning, as 'and then' [Hossack]
     Full Idea: The sentence connective 'and' also has an order-sensitive meaning, when it means something like 'and then'.
     From: Keith Hossack (Knowledge and the Philosophy of Number [2020], 10.4)
     A reaction: This is support the idea that orders are a feature of reality, just as much as possible concatenation. Relational predicates, he says, refer to series rather than to individuals. Nice point.