6th Meeting6th Meeting

FALLACIES IN LOGICFALLACIES IN LOGIC

Sense of Fallacy

Fallacy is a type of argument thatmay seem to be correct, but thatproves on examination not to be

so.

Kinds of informal fallacyKinds of informal fallacy

Meaning of the fallacy of relevance

The mistaken arguments rely on premises that may seem to be relevant to the conclusion but in fact are not.

.. Kinds of Relevance Fallacy

When it is argued that a proposition is true

on the ground that it has not been prove

false, or when it is argued that a proposition

is false because it has not been proved true.

Argument from ignorance (ad ignorantiam)

Example:This is used in a criminal court, where a suspect is presumed innocent until

proved guilty

When the premises of an argument appeal to some party or parties having no legitimate claim to authority in the matter at hand.

Appeal to inappropriate authority (ad verecundiam)

Example:But can you doubt that air has weight when you have the clear testimony of Aristotle affirming that all the elements

have weight including air, and excepting only fire?

Complex questionComplex question

When a question is asked in such a way as

to presuppose the truth of some assumption

buried in that question.

Example:Lawyer: the figure seem to indicate that your sales

increased as a result of these misleading advertisements. Is that correct?

Witness: they did not.

Lawyer: But you do admit, then, that your advertising was misleading. How long have you been engaging in practices like these?

Argument against the person (Argument against the person (ad ad hominemhominem))

When an attack is leveled not at the calims or conclusions of an opponent, but at person of the opponent.

Two forms of it:1. Abusive ad hominem: When the attack is directly against

a persons, seeking to defame or discredit them, it is called an “abusive ad hominem.”

2. Circumstantial ad hominem: When the attack is indirectly against persons, suggesting that they adopt their views chiefly because of their special circumstances or interests, it is called a “circumstantial ad hominem.”

Example:For, if the distinction of degrees is infinite, so that there is among them no degree, thatn which no higher can be found, our course of reasoning reaches this conclusion: that the multitude of natures themselves is not limited by any bounds. But only an absurdly foolish man can fail to regard such a conclusion as absurdly foolish. There is, then, necessarily some nature which is so superior to some natures, that there is none in comparison with which it is ranked as inferior.

AccidentAccident

When one applies a generalization to an

individual case that it does not properly

Govern.

Example:

It has been a common that candidate invites politician to hear the competency of the candidate. I also socialized my competency as the candidate of the Bank of Indoesia. So I did not do any mistake

Converse accidentConverse accident

When one moves carelessly or too quickly

from a single case to an indefensibly broad

Generalization

Example:Take my son, Martyn. He’s been eating fish and chips his whole life, and he just had a cholesterol test, and his level is below the national average. What better proff could there be than a frier’s son?

False causeFalse cause

When one treats as the cause of a thing

what is not really the cause of that thing; or

more generally, when one blunders badly in

reasoning based on causal relations.

Example: beating drums or kentongan is the cause of the sun’s reappearance after solar eclipse.

Appeal to pity (Appeal to pity (ad misericordiamad misericordiam))

When careful reasoning is replaced by

devices calculated to cause sympathy on

the part of the hearer for the objects of the

speaker’s concern.

Example: all of us cannot be famous, because all of us cannot be well known.

Appeal to force (Appeal to force (ad baculumad baculum))

When careful reasoning is replaced with

direct or insinuated threats to cause the

acceptance of some conclusion.

Example:The President continues to have confidence in the Attorney General and I have confidence in the Attorney General and you ought to have confidence in the Attorney General, because we work for the President and because that’s the way things are. And if anyone has a different view of that, or any different motive, ambition, or intension, he can tell me about it because we’re going to have to discuss your status

Irrelevant conclusionIrrelevant conclusion (ignoratio elenchi(ignoratio elenchi))

When the premisses miss the point,

purporting to support one conclusion while in

fact supporting or establishing another

Example:

“Veterans have alwys a strong voice in our government”. President Reagan said all too accurately, adding the non sequitur: “It’s time to give them the recognition they so rightly deserve.

Fallacies of ambiguityFallacies of ambiguity

The mistaken arguments are formulated in

such a way as to rely on shifts in the meaning

of words or phrases, from their use in the

premisses to their use in the conclusion.

Five types of it:

1. Equivocation

2. Amphiboly

3. Accent

4. Composition

5. Division

EquivocationEquivocation

When the same word or phrase is used with

two or more meanings, deliberately or

accidentally, in the formulation if an

Argument.

AmphibolyAmphiboly

When one of the statements in an argument

has more than one plausible meaning

because of the loose or awkward way in

which the words in that statement are

combined.

AccentAccent

When a shift of meaning arises within an

arguments as a consequence of changes in

the emphasis given to its words or parts.

CompositionComposition

This mistake is made:

a. When one reasons mistakenly from the attributes of a part to the attributes of the whole, and

b. When one reasons mistakenly from the attributes of individual member of some collection to the attributes of the totality of that collection

Example:Since every ship is ready for battle, the whole fleet must be

ready for battle.

DivisionDivision

This mistake is made:

a. when one reasons mistakenly from the attributes of a whole to the attributes of one of its parts, and

b. when one reason is mistakenly from the attributes of a totality of some collection of entities to the attributes of the individual entities themselves.

Example: Humans are mortal. Socrates is a human. So Socrates is mortal.

1.Seeing that eyes and hand and foot and every one of our members has some obvious function, must we not believe that in like manner a human being has a function over and above these particular function?

2. But space is nothing but a re

ation. For, in

the first place, any space must consist of parts; and if the parts are not spaces, the whole is not space.

• Thomas Carllyle said of Walt Whitman that he thinks he is a big poet because he comes from big country