chapter 4 Flashcards
what is aristotelian logic
based on principles to deduce truth
uses syllogistic reasoning, which involves presenting two premises and sharing a common term of the premises
conjuctive statements
when statement A has a single premise statement B has a single premise and C conjoins them A: Arnd left work early B: Arnd is in the pub C: Arnd left work early and is at the pub
A: Arnd left work early
B: Arnd is in the pub
C: Arnd left work early and is at the pub
conjunctive statement
when statement A has a single premise
statement B has a single premise
and C conjoins them
what are the 4 propostitions
modus ponens
modus tollens
modus tellendo tollens
hypothetical syllogism
“mood that affirms”
modus ponens
A: If p(arnd left work early) then q(he is in the pub)
B: Arnd left work early
C: Arnd is at the pub
modus ponens
A: if then statements q is antecedent p consequent statement B: affirms antecedent C: affirms the consequent statement
modus tollens
mood that denies
A: if p(arnd left work early), then q(he is in the pub)
B: Arnd is not in the pub
C: arnd did not leave work early
modus tollens
premise a. is presented as a conditional statement “if p, then q”
premise b. negates the consequent statement in premise a.
conclusion c. negates the antecedent statement of premise a.
a. p(Either Arnd will pay the fine) or q(he will go to jail) (but not both).
b. Arnd didn’t pay the fine.
c. Arnd will go to jail.
Disjunctive syllogism exclusive varient
premise a. is in the form of two assertions “p” and “q” linked by the word “or”
premise b. takes the negation of the first assertion “p” in premise a.
conclusion c. restates the second assertion “q” in premise a.
A: p(Either Arnd is at work) or q(he is at the pub) (or both).
B: Arnd is not at work (in which case he may also be at work).
C: Arnd is at the pub (and he may be at work too).
Disjunctive syllogism (inclusive varient) premise a. is in the form of two assertions “p” and “q” which follow the word “either” and are linked by the word “or premise b. takes the negation of the first assertion “p” in premise a. conclusion c. restates the second assertion “q” in premise a.
A. If Arnd left work early, then he is in the pub.
B. If Arnd is in the pub, then he is drinking beer.
C. Arnd left work early, he is drinking beer.
Hypothetical syllogism
premise a. is presented as a conditional statement “if p, then q”
premise b. takes the consequent statement in premise a. as its antecedent and adds a new consequent statement
conclusion c. affirms the antecedent statement of premise a., as well as the antecedent and consequent statements of premise b
posteriori truth
whether something corresponds with reality
priori truth
whether the statment conforms to propostional logic
necessary truths
tied to propositional logic and cannot be denied without creating contradictions which lie in reality
form of priori truth
contingent truths
tied to empirical reality and can be denied on the basis of new facts
form of posteriori truth
