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Lecture 8

PHI 1101 Lecture Notes - Lecture 8: False Dilemma, Peer Pressure, Loaded Question


Department
Philosophy
Course Code
PHI 1101
Professor
Mark Brown
Lecture
8

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Chapter 8: Faulty Reasoning
Certain types of defective arguments happen so frequently that they have been
given names.
These are known as fallacies, and such arguments are said to be
‘fallacious’.
Fallacy: An error in reasoning.
Fallacies can seem plausible.
They are psychologically persuasive, though logically powerless.
We study fallacies because we need to be able to detect them.
Common Fallacies
1. Appeal to Ignorance: arguing that a lack of evidence proves something.
In one type of this fallacy, the problem arises by thinking that a claim must be true
because it hasn’t been shown to be false.
Example:
‘No one has shown that ghosts aren’t real, so they must be real.’
The problem is that lack of evidence is supposed to prove something—but it
can’t.
A lack of evidence alone can neither prove nor disprove a proposition.
A lack of evidence simply reveals our ignorance about something.
2. When a claim comes from someone deemed to be an expert who in fact is not an
expert, we commit the fallacy known as the appeal to inappropriate authority.
Because someone is an expert in one field does not mean that he or she is
necessarily an expert in another.
This point is not that these experts can’t be right, but that their
expertise in a particular field doesn’t give us reason to believe
them in all things.
Example: My lawyer says that the new treatment for MS is no good. I guess she’s
right.

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3. The fallacy of appeal to general belief: arguing that a claim must be true merely
because a substantial number of people believe it.
Examples:
‘Of course the war is justified. Everyone believed that it’s justified.’
‘The vast majority of Canadians believe that the earth is flat, so how could
you doubt it?’
As far as the truth of a claim is concerned, what many people believe is
irrelevant.
4. The fallacy of appeal to popular attitudes and emotions:
Peer pressure: pressure, from one’s peers, to believe or do the things the group
does.
Example: All your friends think your views on politics are ridiculous. That should be
proof enough that you are wrong.
Another kind of group influence is the belief that ‘our group’ is the ‘best’.
Our religion, political party, generation, social class, country, ethnic group,
etc.
Usually this is based on too little information; that is, it is based on
prejudice (pre-judging).
Example: We can’t allow these people to move into this
neighbourhood. They’re not like us.
5. The gambler’s fallacy
Thinking that previous events can influence the probabilities in the random event
at hand.
6. The false cause fallacy (post hoc): Confusing cause with temporal order
This is a very common logical fallacy.
Causes do precede their effects.
But that doesn’t mean that one thing following another is
always a case of causation.
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