The Slippery Slope

by Tim Harding

A slippery slope argument may or may not be a fallacy, depending on whether the argument is logical.  The argument typically states that a relatively small first step will inevitably lead to a chain of related events culminating in some significant consequence, much like an object given a small push over the edge of a slope will slide all the way to the bottom.  

A slippery slope argument has the following form:

Premise: Event X has occurred (or will or might occur).

Conclusion: Therefore consequence Y will inevitably happen.

The strength of such an argument depends on whether or not one can demonstrate a chain of cause and effect leading to the significant consequence.  If no such chain can be demonstrated, the argument becomes a fallacy. This is especially so in cases in which there is a significant number of steps or gradations between one event and another, which increases the probability of the chain of cause and effect being broken. On the other hand, if the chain of cause and effect can be adequately demonstrated to be unbroken, the argument is logical.

The fallacious form of this argument has traditionally been called The Camel’s Nose, because of the image of a sheik whose camel sticks its nose into his tent on a cold night.  The idea is that the sheik is afraid to let the camel put its nose into the tent because once the beast puts in its nose, it will inevitably put in its head, and then its neck, and eventually its whole body.[1] However, this sort of thinking does not allow for any possibility of stopping the process. It simply assumes that, once the nose is in, the rest must follow — that the sheik can’t stop the progression once it has begun — and thus the process is inevitable.[2]

For instance, if one were to argue,

“If we allow the government to infringe upon our right to privacy on the Internet, it will then feel free to infringe upon our privacy on the telephone. After that, FBI agents will be reading our mail. Then they will be placing cameras in our houses. We must not let any governmental agency interfere with our Internet communications, or privacy will completely vanish in the United States.”

Such thinking is fallacious; no logical proof has been provided yet that infringement in one area will necessarily lead to infringement in another, no more than a person buying a single can of Coca-Cola in a grocery store would indicate the person will inevitably go on to buy every item available in the store, helpless to stop herself.[2]

A currently topical example is that one of the arguments against same-sex marriage is that it will lead to a demand for the adoption of children by same-sex married couples.  It is argued that such a demand will be difficult to resist under anti-discrimination legislation; and so the way to prevent such adoptions is to resist same-sex marriage.  There are arguments for and against the need for children to have a relationship with both and father and a mother, but these arguments are not critical to whether or not the slippery slope argument is fallacious.  If there will be no irresistable demand for the adoption of children by same-sex married couples, then the slippery slope argument is clearly fallacious in this case.

Notes and references

[1] The Camel’s Nose fallacy is sometimes described as being based on an old Arabian fable or proverb; however this provenance is doubtful. It is more likely to be a Victorian English invention.

[2] Makethestand.com Learning to Reason Clearly by Understanding Logical Fallacies. Posted 19/7/07. Viewed 9/3/14.

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