Lecture Eight: Fallacies Part Two
November 9, 2011
Fallacy Six: Self-Evident Truth
Definition - This fallacy is committed when the arguer presents their argument as self-
evident (“everybody already knows...”), and therefore does not need to prove it.
This fallacy violates both the argument principle and the reason principle.
It implies that whoever does not believe the argument, or who does not agree that it is
self-evident isn’t intelligent or is deficient in some other way.
“Women should not be in decision-making positions. Isn’t it obvious that they are more
emotional than men? And since women are more emotional, they are likely to make
decisions based on emotions rather than reasons”
The indicator phrase in this example is “Isn’t it obvious...”.
- It implies that the person being argued to should already believe to be true what the
arguer is presenting to them
- It also implies that the conclusion is self-evident, meaning that there is no need for
them to further prove their statements because it is obvious
- If the arguer provides a reason for why they have come to the conclusion, then this
fallacy is not committed
Fallacy Seven: Appeal to Ignorance
Definition: This fallacy is committed when an opponents inability to prove something is
used as proof to justify the arguer’s conclusion.
There are two types of this fallacy
- If you can’t prove it’s right, then it’s wrong
- If you can’t prove its wrong, then it must be right
This is a fallacy because the whole argument is based on a lack of evidence, instead of
using evidence to support the conclusion.
- The fact that there is no evidence to the contrary is used as justification for the
Example “There must be no intelligent life in outer space because nobody has been able to prove
that there is”
This example is attempting to use the lack of proof to justify why the conclusion must be
true. There is no actual proof given to support the conclusion other than the fact that
there is no evidence that points to the contrary.
Fallacy Eight: Loaded Presupposition
Definition: This fallacy is committed when a person makes a claim or asks a question
that has a contentious presupposition in it.
Presupposition: a thing that is assumed to be known before the argument is even
stated (something that the arguer believes to be a common knowledge fact, even if it is
This fallacy occurs in the following situation
- Someone presents multiple issues with the assumption that the answer to one will
automatically imply the answers to the others
This fallacy consists of presenting a claim with a highly doubtful, false or misleading
- It is often committed by asking a question with one or more debatable assumptions
“Why is it that children of divorce are less emotionally stable than children raised in
This has the presuppositions of
- Children of broken homes are emotionally unstable
- That divorce is the cause of why children are emotionally unstable
This questions leads people to believe that there are no other reasons that children are
emotionally unstable, it completely ignores all other factors of emotional instability.
- In order to accept the conclusion and the claims, one must accept the presupposition
of which there may be other assumptions which can be made about it
Fallacy Nine: Begging the Q