Logical_constructions Non_sequitur_(logic)

1 logical constructions

1.1 affirming consequent
1.2 denying antecedent
1.3 affirming disjunct
1.4 denying conjunct
1.5 fallacy of undistributed middle

logical constructions

affirming consequent

any argument takes following form non sequitur

even if premise , conclusion true, conclusion not necessary consequence of premise. sort of non sequitur called affirming consequent.

an example of affirming consequent be:

while conclusion may true, not follow premise:

the truth of conclusion independent of truth of premise – non sequitur , since jackson might mammal without being human. might be, say, elephant.

affirming consequent same fallacy of undistributed middle, using propositions rather set membership.

denying antecedent

another common non sequitur this:

while b can indeed false, cannot linked premise since statement non sequitur. called denying antecedent.

an example of denying antecedent be:

while conclusion may true, not follow premise. reader knows, statement s declarant ethnicity of asia, e.g. chinese, in case premise true conclusion false. argument still fallacy if conclusion true.

affirming disjunct

affirming disjunct fallacy when in following form:

the conclusion not follow premise case , b both true. fallacy stems stated definition of or in propositional logic inclusive.

an example of affirming disjunct be:

while conclusion may true, not follow premise. reader knows, declarant of statement in both city , home, in case premises true conclusion false. argument still fallacy if conclusion true.

*note logical fallacy when word or in inclusive form. if 2 possibilities in question mutually exclusive, not logical fallacy. example,

denying conjunct

denying conjunct fallacy when in following form:

the conclusion not follow premise case , b both false.

an example of denying conjunct be:

while conclusion may true, not follow premise. reader knows, declarant of statement neither @ home nor in city, in case premise true conclusion false. argument still fallacy if conclusion true.

fallacy of undistributed middle

the fallacy of undistributed middle fallacy committed when middle term in categorical syllogism not distributed. syllogistic fallacy. more form of non sequitur.

the fallacy of undistributed middle takes following form:

it may or may not case zs bs , in either case irrelevant conclusion. relevant conclusion whether true bs zs, ignored in argument.

an example can given follows, b=mammals, y=mary , z=humans:

note if terms (z , b) swapped around in first co-premise no longer fallacy , correct.