A Class Room Logic: Deductive and Inductive, with Special Application to the Science and Art of TeachingMcNair, George Hastings
Philosophy
A Class Room Logic: Deductive and Inductive, with Special Application to the Science and Art of Teaching
McNair, George Hastings
Logic
_Arranged, and antecedent and consequent indicated._
If one believes in the tenets of the democratic party (antecedent),
then he should vote for its candidates (consequent);
And A does believe in these tenets,
∴ He should vote for its candidates (I have asked him to vote for
me).
The minor premise affirms the antecedent and thus the argument is valid
according to rule.
_Reduced to the categorical_:
M
A One who believes in the tenets of the democratic party should
――――――――――――――――――――――――――――――――――――――――――――――――――――――
G
vote for its candidates,
S M
A A believes in these tenets,
―
S G
A ∴ A should vote for its candidates.
―
{ A
Reduced to the categorical gives mood { A in the first figure and this
{ A
we know to be valid.
(3) “If the weather had not been pleasant, I could not have come; but
as the weather is pleasant, here I am.”
_Arranged and antecedent and consequent indicated_:
If the weather had not been pleasant (antecedent), I could not have
come (consequent);
The weather is pleasant,
∴ I have come (here I am).
The minor premise _denies_ the antecedent and consequently the argument
is invalid according to the rule. (An affirmative minor premise denies
a negative antecedent.)
_Reduced to the categorical_:
E Unpleasant weather would not permit me to come,
E This weather is not unpleasant,
A ∴ This weather enabled me to come.
Fallacy of two negative premises.
(4) “If one pays his debts, he will not be ‘black-listed’; but since
you are ‘black-listed,’ I conclude that you have not paid your debts.”
_Arranged logically and antecedent and consequent indicated_:
If one pays his debts (antecedent), he will not be “black-listed”
(consequent);
You are “black-listed,”
∴ You have not paid your debts.
The minor premise denies the consequent hence the argument is valid.
_Reduced to categorical form_:
G M
E No one who pays his debts is black listed,
―――――――――――――――――――――― ――――――――――――
S M
A You are black listed,
―――
S G
E ∴ You have not paid your debts.
――― ―――――――――――――――
{ E
The mood { A in the second figure is valid.
{ E
(5) “Men would do right for the sake of themselves, if they appreciated
the law of retribution; but they never think of that.”
_Arranged, completed, and tested_:
If they appreciated the law of retribution (antecedent), men would
do right for the sake of themselves (consequent);
But they do not appreciate the law of retribution (never think of
that),
Hence they do not do right for the sake of themselves.
Fallacy of denying the antecedent.
_Reduced to the categorical_:
Public-domain text, read in full here on John Shaqi.
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