Formal fallacies and fallacies of language - PowerPoint Presentation

Slide1

Formal fallacies and fallacies of language

Kimberly Wyatt – Critical ReasoningSlide2

Consistency and inconsistency

Flip-flop

Waffle

Flakey

Consider new information

Change your own mind

Is it simply pandering?Slide3

Consistent Individual claims

It is consistent if it is at least

possible

for it to be truee.g. “Read my lips, no new taxes”Slide4

Inconsistent individual claims

If it simply cannot be true, then the claim is inconsistent.

e.g. It was raining on my window today, but not

raining

raining

.Slide5

Consistency of a person

Remember that because a

person

has been inconsistent, it does not speak to their position

on matters.

We like to believe that if a person is inconsistent, so are their positions on important things. This is a fallacy. We must judge on the

merits

of their position. Otherwise it is the

argumentum ad hominem

. Judging the argument “by the man” not the actual argument.Slide6

Miscalculating probabilities

One independent event

cannot

affect the outcome of another.

As an example, since a die (dice) has 6 sides, you would multiply 1/6 times 1/6 to get a 1 in 36 chance of getting 2 snake eye rolls. Not 2 in 6 as some assume.Slide7

Gambler’s fallacy

A fallacy wherein the speaker doesn’t realize that independent events are truly

independent

e.g. Separate coin flips have nothing to do with each other.Slide8

Overlooking prior probabilities

A fallacy wherein we overlook something in a probability that everything else being equal, is it’s prior probability.

e.g. Not taking into account all the things that can change our probabilities outcome.Slide9

Overlooking false positives

This is a fallacy in calculating the probability of something occurring.

Taking a seemingly large sample that in reality isn’t that large and using bad math to come to completely wrong conclusions.