How to Spot and Avoid the Slippery Slope Fallacy in Everyday Conversations

Ever hear of someone warning you of doing something because it could lead to a "slippery slope"? Enter: the slippery slope fallacy—which argues that one relatively harmless event will lead to a chain reaction that results in an extreme (often undesirable) outcome.

The outcome is usually described as inevitable unless steps are taken to prevent it, even though there are usually only two events discussed: the original event and the outcome. There are many examples of the slippery slope argument in everything from politics to law to business to social examples.

Let's take a look at the impact and consequences of the slippery slope fallacy, learn how to avoid the fallacy, and explore some examples of how it plays out.

Understanding the Slippery Slope Fallacy

The slippery slope argument asserts that an initial action will eventually lead to an extreme result. However, slippery slope arguments aren’t always fallacious. Patrick J. Hurley, emeritus professor of philosophy at the University of San Diego and writer of the books "Religion, Power, & Illusion: A Genealogy of Religious Belief" and "A Concise Introduction to Logic," explains that if the person arguing for the slippery slope sees logical connections that exist, these arguments can be valid.

For example, Hurley explains, "a [recovering] alcoholic [could] argue to himself: 'I must never take another drink. Not even a small one. If I take that first drink, then I’ll want another. The first few drinks may be tiny ones, but soon they will become jumbos. Before long, I’ll be throwing them down, one after another, and then I’ll be hooked, just as I was before I quit. In the end, alcohol may end up killing me.' This is probably a good argument. The causal connections that link one drink with another probably really exist [in this case]. For the slippery slope fallacy to occur, at least one of the causal connections must be weak or nonexistent."

There are three kinds of slippery slopes:

Causal Slopes

Causal slopes suggest that a relatively minor action now will result in a sequence of events that result in a major action later. For instance, one could argue that if we give one student extra time on the test, we might give everyone perfect scores later, regardless of their effort. Causal slippery slopes require at least two events, the first event and the last one, although any number of events can occur in between either because they are implied or because they’re explicitly brought up. This kind of slippery slope is often fallacious because it ignores or understates the uncertainty ingrained in getting from the minor starting event to the major end event.

Precedential Slopes

Precedential slopes argue that if we set a precedent by treating something relatively minor a specific way now, we’ll have to treat something major the same way later. This is all about treating cases in a consistent manner. Licensed clinical psychologist Amanda Etienne, PsyD provides an example, "If we legalize marijuana, we will end up legalizing 'harder drugs,' like heroin." This kind of slippery slope is often fallacious because it ignores our ability to treat cases differently.

Conceptual Slopes

These revolve around the idea that if it’s possible to transition from point A to point B in a series of small, nearly indistinguishable steps, then there’s no meaningful difference between the two. For instance, if we allow euthanasia for people on the verge of death, we might as well allow it for everyone. This kind of slippery slope is often fallacious because it ignores our ability to distinguish between two things even if they are relatively similar.

Impact and Consequences of the Slippery Slope Fallacy

The slippery slope argument is not always flawed, but when it is, it can be insidious. It is often used to promote fear and anxiety and to shut down more subtle arguments. As Etienne explains, “The fallacy is often used in fear-mongering attempts, as it often shuts down nuanced discussion by encouraging an all-or-nothing view of the phenomenon in question. It can, unfortunately, be used to justify restrictive policies and procedures.”

How to Identify and Avoid the Slippery Slope Fallacy

You can do various things to identify and avoid the slippery slope fallacy when it is being used by others. These include:

1. Call out a lack of evidence that one small thing will lead to a big thing. “Look at arguments that claim one thing will inevitably lead to another,” says Etienne. “These arguments usually do not provide evidence [or provide evidence] that is unrelated to outcome.”
2. Examine the transition between the start and end points of the slope and realize the outcome is not inevitable. “When considering the impact of an original event,” explains Etienne, “consider intervening factors that may alter the course proposed by the argument.”
3. Think about how realistic the arguments are. “Consider whether the claimed occurrences between the original event and the outcome are realistic and/or likely given the context,” observes Etienne.
4. Look at what the people making the argument get out of it. "The slippery slope fallacy is used most often by people who have something to gain by it," says Hurley. "So look at the flow of money and power."

Furthermore, as Etienne points out, “in many instances, people will actually use the phrase 'slippery slope' when using this fallacy.” If someone uses the phrase “it’s a slippery slope,” be sure to listen carefully to their argument and challenge it if need be.

How to Avoid the Fallacy in Your Own Arguments

Much like in other people’s arguments, you can look for instances of the slippery slope fallacy in your own arguments, too. Take the following steps to avoid the fallacy:

• Just like in the tips above, Etienne says, you’ll want to “consider intervening factors that may alter the course proposed by your argument.”
• Instead of focusing on the consequences, “focus on your argument’s points,” observes Etienne. “Slippery slope is often a defensive strategy that uses fear of the alternative over the merits of one’s own argument.”
• Avoid arguments that suffer from a lack of support. "Make sure that the causal connections that your argument depends on really exist," says Hurley. "Just because one thing happens before another does not mean that the first thing causes the second thing."

Examples of Slippery Slope Fallacy in Different Contexts

There are many examples of the slippery slope fallacy. Here are a few:

• “First we loosen up the laws against abortion. Next, mark my words; we'll take seriously the option of infanticide in certain severe cases. And this will lead us to look with favor on euthanasia for those we deem social deviants.”
• “I don't think it's a good idea to lower the drinking age. Next thing we know, kids will get to drive at age 10 and vote at 15.”
• "Obamacare is an attack on our liberties and the first step in a socialist conspiracy!"
• "In the lead-up to the Vietnam War in the 1960s, politicians argued that if Vietnam were to fall to the communists, then next it would be Cambodia, then Thailand, and then Burma," says Hurley. "In the end, all of Southeast Asia would become communist. This argument and others like it led to the US spending billions on the war."
• "Prior to the abolition of slavery," observes Hurley, "a debater named N. L. Rice argued in 1845 that if slavery were abolished, then former slaves would be elected to public office. Colored men would take over the state legislatures, then the judiciary, and then the office of governor."
• "Politicians opposed the adoption of Social Security in the 1930s by arguing that Social Security is welfare, welfare leads to socialism, and socialism leads to communism. In the end, the United States will be a communist country," explains Hurley.
• "Religious leaders have argued that young people should never masturbate, because if they do, soon they will be having sex," says Hurley. "Then illegitimate children will pop up everywhere. These children will rob and steal just to survive, crime will explode, the jails will burst from overcrowding, and society will collapse."

Common Misconceptions about the Slippery Slope Fallacy

A common misconception about the slippery slope fallacy is that it’s not a fallacy at all. As Etienne says, “I have heard people use ‘it’s a slippery slope’ as a rationale for their position without realizing that they are not providing any evidence.” The slippery slope fallacy is a fallacy, but slippery slope arguments can be reasonable too, as Hurley observes. You have to be able to look at the argument and figure out if the person offering it is providing support and examples for it.

For example, at a 2019 press conference, Donald Trump said, “A lot of the people that put me where I am are strong believers in the Second Amendment, and I am, also. And we have to be very careful about that. You know, they call it the ‘slippery slope,’ and all of a sudden, everything gets taken away. We’re not going to let that happen.”

Whatever you think of Donald Trump, this argument leaves something to be desired. It lacks any evidence or supporting statements to prove itself.

Takeaway

The slippery slope fallacy suggests that a small starting point will lead to a larger, undesirable end point. Though the slippery slope argument isn’t always a fallacy, if the person arguing it does not provide evidence to justify the slippery slope, if they overstate their conclusions, and if they say “it’s a slippery slope” without providing support, their argument is likely fallacious.