Definition

This is when we argue A will cause B, and B will lead to undesirable C. Since we do not want C, we should avoid A.

All slippery slope fallacies present a chain of reasoning in which the first step leads to others, but no good justification is given for why the first step will lead to the others.

Examples

1) If I loan you a dollar today then you will eventually ask me for ten dollars and then one hundred dollars. I do not want that to happen, so I cannot give you the one dollar loan (Law, 2003).

2) Humans will eventually be marrying trees and raccoons if we allow homosexual marriage.

3) All types of murder will become legal if we legalize voluntary active euthanasia.

4) I must accept the existence of soul if I believe some form of dualism.

Notice the slippery slope could be much longer (A leading to D and E) or shorter (A leading only to B).

Search Youtube for “Direct TV Commercials” to find several humorous slippery slope commercials.

Discussion

It is important to remember that all above examples are good arguments if there is good evidence for why A will lead to B, B will lead to C, and so on. It is only a fallacy if I do not give good reasons for why this slide will occur, or if there are no good reasons for why the end of the chain is undesirable.

In short, not every slope is fallacious.

Exercise

  1. Give an example of a slide/slope that is not a slippery slope fallacy.
  2. Create or find a few examples of the slippery slope fallacy.
  3. Read the following argument and discuss whether it is a slippery slope fallacy. "If we let the communists take Vietnam, they will then take Laos, Cambodia, and much of the eastern world. Communism will continue to spread across the world until it is on our borders thereby posing an immediate threat to our security. Therefore, we shouldn’t let the communists take Vietnam."

Answers

  1. If I push the domino, it will fall and hit the second, the second will fall and hit the third, and so on.
  2. Answers will vary.
  3. Answers will vary. This debate occurred in the 1960s and illustrates how people can disagree about whether a slide is legitimate or fallacious.

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