Sign In Sign Up
Home / Informal Fallacies / Slippery Slope

Slippery Slope

informal Fallacy

The slippery slope fallacy occurs when someone argues that a relatively small first step will inevitably lead to a chain of related events culminating in a significant (usually negative) outcome, without providing adequate justification for why each step in the chain must follow.

Example of Slippery Slope

  • If we let our child out of his room, eventually he will want to leave the house, and will end up on the street. If he is walking around on the street then he will be snatched up by a stranger and sold into slavery in a remote region of the world. Though it may be true that the child might leave the house and go on the street, ending up as a slave in a remote part of the world is comically unlikely. Each step in the chain is treated as inevitable when it is not.
  • If we allow students to use calculators in math class, they'll never learn basic arithmetic. Then they won't be able to handle any math at all, and eventually our entire society will become mathematically illiterate. While over-reliance on calculators could have some effect on learning, the leap to total societal mathematical illiteracy ignores many intervening factors and is a dramatic exaggeration.

In more detail

The Slippery Slope fallacy is a logical fallacy in which someone argues that a single action or event will set off a chain reaction of increasingly serious consequences, ultimately leading to a drastic outcome. The key problem with this reasoning is that it treats each step in the chain as inevitable, without providing adequate evidence or justification for why one event must necessarily lead to the next. Important intervening factors, safeguards, or alternative outcomes are ignored.

For example, if a person argues that legalizing one form of gambling will inevitably lead to the legalization of all forms of gambling and ultimately to the collapse of public morality, they are committing the Slippery Slope fallacy. While it may be worth considering potential consequences, each step in the chain requires its own justification—merely asserting that one thing leads to another does not make it so.

It is worth noting that not all "slippery slope" arguments are fallacious. If someone can provide strong evidence that each step in the chain is likely to follow from the previous one, the argument may be legitimate. The fallacy occurs specifically when the causal links between steps are assumed rather than demonstrated, and when the argument relies on fear or exaggeration rather than evidence.

When evaluating a slippery slope argument, ask: Is there good reason to believe each step will follow from the last? Are there factors that could prevent the chain from continuing? Is the final consequence being exaggerated to create an emotional reaction? Answering these questions can help distinguish a reasonable concern about consequences from a fallacious slippery slope.