The aim of this tutorial is to help you learn to identify the types of fallacious reasoning discussed in
Chapter 6.
Chapter 6 discusses fallacies of insufficient evidence.
These are fallacious arguments in which the premises, though logically relevant to the conclusion, fail to provide sufficient evidence to support the conclusion.
In this tutorial you will see examples of various fallacies of insufficient evidence. Though not every type of fallacy of insufficient evidence is illustrated, the techniques demonstrated here apply to all the fallacies discussed in
Chapter 6.
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Of course angels exist. Do you know of any proof that they don't?
The first step in identifying a fallacious argument is to identify the conclusion of the argument. An argument relies on an inference linking the truth of the premises to the truth of the conclusion. Fallacious reasoning can often be spotted by noting how the argument fails to make this linkage.
So, what is the conclusion of this argument?
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Of course angels exist. Do you know of any proof that they don't?
Angels exist.
A successful argument must have premises that provide good reasons for accepting the conclusion. In this argument, the only "proof" offered that angels exist is the fact that no one has proven that they don't exist. Based on what you have learned in this chapter, what fallacy does this argument commit?
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Of course angels exist. Do you know of any proof that they don't?
The fallacy of appeal to ignorance.
The fallacy of appeal to ignorance occurs when an arguer claims that something is true because no one has proven it false, or conversely, that something is false because no one has proven it true.
In this argument, the arguer provides no positive evidence to support her conclusion.
Instead, she treats the lack of evidence against her claim as evidence that her claim is true. But the fact that we don't know that a claim is false doesn't show that the claim is true. For example, the fact that you can't prove that invisible aliens aren't spying on you doesn't provide good reason to believe that they are spying on you. Arguments must be supported by evidence, and a lack of evidence is not evidence!
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I've taken two psychology courses at this university, and both were taught by graduate teaching assistants. I guess all psychology courses at this university are taught by graduate teaching assistants.
The first step in evaluating any argument is to identify the conclusion. What is the conclusion of this argument?
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I've taken two psychology courses at this university, and both were taught by graduate teaching assistants. I guess all psychology courses at this university are taught by graduate teaching assistants.
All psychology courses at this university are taught by graduate teaching assistants.
An argument is a good one only if the premises provide sufficient evidence to accept the conclusion. Does the premise of this argument provide sufficient reason to accept the conclusion?
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I've taken two psychology courses at this university, and both were taught by graduate teaching assistants. I guess all psychology courses at this university are taught by graduate teaching assistants.
It does not! The arguer is drawing a general conclusion based on very limited experience. Given what you learned in this chapter, what fallacy does the arguer commit?
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I've taken two psychology courses at this university, and both were taught by graduate teaching assistants. I guess all psychology courses at this university are taught by graduate teaching assistants.
The fallacy of hasty generalization.
The fallacy of hasty generalization occurs when an arguer draws a general conclusion (i.e., a claim of the form "All A's are B's" or "Most A's are B's") from a sample that is biased or too small.
In this argument, the arguer's sample is too small. The fact that he has taken two psychology courses that were taught by graduate teaching assistants does not provide good reason to believe that all psychology courses at the arguer's university are taught by graduate teaching assistants. Thus, the arguer's reasoning is fallacious.
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Once your kids are watching cartoons, they’re also watching those toy commercials. If they see the commercials they’ll want the toys; before you know it, they’re obsessed with the toys and you’ve lost all control over them. So don’t let your kids watch cartoons.
Again, the first step is identifying the conclusion. Next, inspect the way the argument tries to support this conclusion. Ask yourself what the support is and how it is tied to the conclusion.
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The conclusion, readily identified by the indicator
“ so,
” is “ Don’t let your kids watch cartoons .”
Now, inspect the way the argument supports this conclusion .
Watching
Cartoons.
Watching Toy
Commercials.
Wanting
Toys.
Being Out
Of Control.
Being Obsessed
With Toys.
What do you think of this reasoning?
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Watching
Cartoons.
Watching Toy
Commercials.
Wanting
Toys.
Being Out
Of Control.
Being Obsessed
With Toys.
If watching cartoons will lead inexorably to your kids being out of control, then the conclusion is probably a reasonable one. However, will all of these intermediate steps necessarily happen? Doesn’t the arguer need to prove they will? Yes she does !!
There is fallacious reasoning at work here. What kind is it?
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Again, this tutorial has not looked at every type of fallacious reasoning from Chapter 6. However, as you have seen, the basic strategy for identifying these fallacies is the same in every case.
1.
Find the conclusion.
2.
Note the evidence cited and how it applies to the conclusion. Is it relevant? Do the premises, if true, provide sufficient evidence to support the conclusion?
3.
Realize that the specific names for the fallacies were created to fit common sorts of fallacious reasoning. Even without studying logic, you can often see that an argument is fallacious, and since you have studied logic, you can connect the logical flaw with the name.
This is the end of this tutorial .