JOHN CORCORAN AND HASSAN MASOUD, Three-logical-theories redux.
The 1969 paper, “Three logical theories”
, considers three logical systems all based on the same interpreted language
and having the same semantics.
The first, a logistic system LS, codifies
tautologies (logical truths)—using tautological axioms and tautology-preserving
rules that are not required to be consequence-preserving.
The second, a consequence system CS, codifies
valid premise-conclusion arguments—using tautological axioms and
consequence-preserving rules that are not required to be cogency-preserving
. A rule is cogency-preserving if
in every application the conclusion is known to follow from its premises if the
premises are all known to follow from their premises.
The third, a deductive system DS, codifies deductions, or cogent argumentations —using cogency-preserving rules. The derivations in a DS represent deduction: the process by which conclusions are deduced from premises, i. e. the way knowl ... (read more)