3.3 fallacies of weak induction University of Wisconsin-Oshkosh

This fallacy is a variety of the argument form “arguments from authority” and occurs
when the cited authority or witness is not trustworthy/lacks credibility.
Among the reasons for doubting the cited authorities are:
○ he/she is not an expert in the field;
○ he/she has potential bias (record of prejudice) or some other motive to lie (such
as an economic interest in the outcome);
○ he/she suffers from a lack of cognitive or perceptual ability (e.g., senility,
blindness) relative to the premises of the argument.
10. APPEAL TO IGNORANCE
★ When the premises of an argument state that nothing has been proved one way or the
other about something, and then than conclusion makes a definite assertion about that
thing.
★ The issue usually involves something that is incapable of being proved or something that
has not yet been proved.
★ Ths fallacy comes in two basic forms:
P has not been proved P has not been disproved
So P is false So P is true
★ In other words, from the fact that some proposition has not been proved (or disproved), it
is concluded that we do know that it is false (or true).
★ There are two main exceptions:
a. It is not fallacious to conclude that a hypothesis is probably false/true if there has
been a failure by qualified researchers over a significant amount of time to
confirm/disconfirm it. And in certain cases, the hypothesis is so simple that no
special expertise is necessary. For instanceNo one — including his closest friends and relatives — has ever seen John smoke
So John is a non-smoker
b. Courtroom procedure in the U.S. and Canada- From the fact that a defendant’s
guilt is not proved beyond a reasonable doubt, it is concluded (properly) that the
defendant is “not guilty”. However, “not guilty” in this context just means “not
proven guilty beyond a reasonable doubt”.

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