vagrant

From Stephen's Guide (8)
Fallacies Involving Statistical Syllogisms

--------------------------------------------------------------------------------
A statistical generalization is a statement which is usually true, but not always
true. Very often these are expressed using the word "most", as in "Most
conservatives favour welfare cuts." Sometimes the word "generally" s used, as in
"Conservatives generally favour welfare cuts." Or, sometimes, no specific word is
used at all, as in: "Conservatives favour welfare cuts."
Fallacies involving statistical generalizations occur because the generalization is not
always true. Thus, when an author treats a statistical generalization as though it
were always true, the author commits a fallacy.

1. Accident

--------------------------------------------------------------------------------
Definition:
A general rule is applied when circumstances suggest that an
exception to the rule should apply.

Examples:
(i) The law says that you should not travel faster than 50
kph, thus even though your father could not breathe, you
should not have travelled faster than 50 kph.
(ii) It is good to return things you have borrowed. Therefore,
you should return this automatic rifle from the madman you
borrowed it from. (Adapted from Plato's Republic, Book I).

Proof:
Identify the generalization in question and show that it is not
a universal generalization. Then show that the circumstances
of this case suggest that the generalization ought not to apply

2. Converse Accident

--------------------------------------------------------------------------------
Definition:
An exception to a generalization is applied to cases where the
generalization should apply.

Examples:
(i) Because we allow terminally ill patients to use heroin, we
should allow everyone to use heroin.
(ii) Because you allowed Jill, who was hit by a truck, to
hand in her assignment late, you should allow the entire
class to hand in their assignments late.

Proof:
Identify the generalization in question and show how the
special case was an exception to the generalization

vagrant

Logic from Stephen's Guide (3)
Slippery Slope

Definition:

In order to show that a proposition P is unacceptable, a sequence of increasingly unacceptable events is shown to follow from P. A slippery slope is an illegitimate use of the "if-then" operator.

Examples:
(i) If we pass laws against fully-automatic weapons, then it won't be long before we pass laws on all weapons, and then we will begin to restrict other rights, and finally we will end up living in a communist state. Thus, we should not ban fully-automatic weapons.

(ii) You should never gamble. Once you start gambling you find it hard to stop. Soon you are spending all your money on gambling, and eventually you will turn to crime to support your earnings.

(iii) If I make an exception for you then I have to make an exception for everyone.

Proof:
Identify the proposition P being refuted and identify the final event in the series of events. Then show that this final event need not occur as a consequence of P.

vagrant

Logic from Stephen's Guide (4)
Complex Question

Definition:

Two otherwise unrelated points are conjoined and treated as a single proposition. The reader is expected to accept or reject both together, when in reality one is acceptable while the other is not. A complex question is an illegitimate use of the "and" operator.

Examples:
(i) You should support home education and the God-given right of parents to raise their children according to their own beliefs.

(ii) Do you support freedom and the right to bear arms?

(iii) Have you stopped using illegal sales practises? (This asks two questions: did you use illegal practises, and did you stop?)

Proof:
Identify the two propositions illegitimately conjoined and show that believing one does not mean that you have to believe the other.

vagrant

Logic from Stephen's Guide (5)
Appeals to Motives in Place of Support

--------------------------------------------------------------------------------
The fallacies in this section have in common the practise of appealing to emotions or other psychological factors. In this way, they do not provide reasons for belief.
The following fallacies are appeals to motive in place of support:

1.Appeal to Force
(argumentum ad baculum)

--------------------------------------------------------------------------------
Definition:
The reader is told that unpleasant consequences will follow
if they do not agree with the author.

Examples:
(i) You had better agree that the new company policy is the
best bet if you expect to keep your job.
(ii) NAFTA is wrong, and if you don't vote against NAFTA
then we will vote you out of office.

Proof:
Identify the threat and the proposition and argue that the
threat is unrelated to the truth or falsity of the proposition.

References:
Cedarblom and Paulsen: 151, Copi and Cohen: 103

2.Appeal to Pity
(argumentum ad misercordiam)

--------------------------------------------------------------------------------
Definition:
The reader is told to agree to the proposition because of the
pitiful state of the author.

Examples:
(i) How can you say that's out? It was so close, and besides,
I'm down ten games to two.
(ii) We hope you'll accept our recommendations. We spent
the last three months working extra time on it.

Proof:
Identify the proposition and the appeal to pity and argue that
the pitiful state of the arguer has nothing to do with the truth
of the proposition.

3.Appeal to Consequences
(argumentum ad consequentiam)

--------------------------------------------------------------------------------
Definition:
The author points to the disagreeable consequences of
holding a particular belief in order to show that this belief is
false.

Example:
(i) You can't agree that evolution is true, because if it were,
then we would be no better than monkeys and apes.
(ii) You must believe in God, for otherwise life would have
no meaning. (Perhaps, but it is equally possible that since
life has no meaning that God does not exist.)

Proof:
Identify the consequences to and argue that what we want to
be the case does not affect what is in fact the case.

4.Appeal to Popularity
(argumentum ad populum)

--------------------------------------------------------------------------------
Definition:
A proposition is held to be true because it is widely held to
be true or is held to be true by some (usually upper crust)
sector of the population.
This fallacy is sometimes also called the "Appeal to Emotion"
because emotional appeals often sway the population as a
whole.

Examples:
(i) If you were beautiful, you could live like this, so buy
Buty-EZ and become beautiful. (Here, the appeal is to the
"beautiful people".)
(ii) Polls suggest that the Liberals will form a majority
government, so you may as well vote for them.
(iii) Everyone knows that the Earth is flat, so why do you
persist in your outlandish claims?

vagrant

Logic from Stephen's Guide (2)
Argument from Ignorance
(argumentum ad ignorantiam)

Definition:

Arguments of this form assume that since something has not been proven false, it is therefore true. Conversely, such an argument may assume that since something has not been proven true, it is therefore false. (This is a special case of a false dilemma, since it assumes that all propositions must either be known to be true or known to be false.) As Davis writes, "Lack of proof is not proof." (p. 59)

Examples:
(i) Since you cannot prove that ghosts do not exist, they must exist.

(ii) Since scientists cannot prove that global warming will occur, it probably won't.

(iii) Fred said that he is smarter than Jill, but he didn't prove it, so it must be false.

Proof:
Identify the proposition in question. Argue that it may be true even though we don't know whether it is or isn't.