How Deduction Can Be Misused

In the next lesson, you will learn about specific ways in which deductive arguments are used incorrectly, whether negligently or deliberately. The better you become at spotting these "logical fallacies," the less likely you will be to accept one as truth.

Simply, a deductive argument is invalid for one of two possible reasons: either or both of the premises are invalid, or the wrong conclusion was reached even though the premises are valid. This example contains a premise that is not true:

All Americans wear sneakers. (Major premise) Harold is an American. (Minor premise) Therefore, Harold wears sneakers. (Conclusion)

Since all Americans do not wear sneakers, the major premise is not true. That makes the conclusion, and therefore the deductive argument itself, invalid.

In this case, the wrong conclusion is reached:

Many Americans wear sneakers.

Harold is an American.

Therefore, Harold wears sneakers.

Note that by restating the invalid premise to make it valid, you have not made the conclusion true. Harold may or may not be in the group of "many" who wear sneakers. The conclusion makes an assumption that goes beyond the information contained in the premises.

Friendly Persuasion

Friendly Persuasion

To do this successfully you need to build a clear path of action by using tools if necessary. These tools would be facts, evidence and stories which you know they can relate to. Plus you always want to have their best interests at heart, in other words, you know what is good for them

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