The fact that we are able to anticipate most of the consequences of our actions is undoubtedly a blessing. However, we can also allow fear or over-cautiousness to make us anticipate events that are not likely to follow. This edges us toward a common error of judgement: the slippery slope.

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This sophism holds that a small (and usually harmless) step in a certain direction will trigger a chain of events that will ultimately lead to a significant, unwanted consequence. As the name of the argument suggests, its distinctive feature is the assumption that, once the first action takes place, the succession of actions triggered by it cannot be halted until the final, devastating result.

An argument that takes different shapes

There are several types of slippery slope arguments1, but the general shape can be easily recognised because it illegitimately uses an “if-then” condition: if A, then B; if B, then C; if C, then D, where D represents the negative result obtained by a succession of actions, after starting from the harmless proposal of A.

Usually, a slippery slope argument is built on a cause-and-effect relationship: “If we agree to reduce the number of jurors from 12 to 10, then we could eventually end up reducing it to two people or even one.”

Another type of slippery slope argument goes like this: if we treat a minor event in a certain way, then we set a precedent that forces us to treat a major issue in the same way. “If we do not treat his minor misconduct severely, we will eventually be unable to treat his serious misconduct, and he will have no respect for his parents.”

The conceptual slippery slope argument suggests that if the transition between two things is possible using a series of small, almost imperceptible steps, then there is no significant difference between the two and should therefore be treated in the same way: “If we allow the euthanasia of animals, there is no reason not to allow it in humans.”

Who employs the slippery slope argument?

In private or public debates (legislative, legal, or media), this argument is used to discourage an initiative, claiming, without sound arguments, that a good decision will create the conditions for a chain of wrong decisions. In general, the slippery slope argument involves exaggeration—sometimes excessive exaggeration—but also an appeal to emotions. Negative emotions, such as fear or hatred, are often evoked, although occasionally positive emotions, such as hope or compassion, can be used to encourage a certain course of action. In general, the slippery slope is used more by critics of an argument and less by its proponents.

The domino effect can be real in some situations, and some actions do trigger others. But intuition alone does not qualify us to say that things are sure to take a certain course. We need evidence and solid logical arguments to show that a certain chain of events is inevitable, or at least, quite probable.

How to dismantle erroneous reasoning

Slippery slope arguments are usually false, and different methods can be used to deconstruct them, depending on the sophism sub-type.

Thus, in the case of the causal slippery slope, the whole reasoning is false if there is no solid evidence that an acceptable change initiated at present will eventually lead to an intolerable one in the future.

“If we allow refugees to enter the country, we will have to accept more and more people over time, and then crime will increase and citizens will no longer be safe.” For the reasoning to be valid, it takes evidence (statistics, studies) to show that the recursive premise is true (generally, the slippery slope operates with three premises: the one that postulates the first step of the sequence; the recursive premise, which describes the slope mechanism, and the third premise, which names the undesirable consequences to which the slope leads). If only one premise is false, the reasoning collapses, regardless of the truth value of the others.

In fact, the intermediate sentences are often not false, but have a certain probability of happening. The longer the chain of arguments, the lower the probability of reaching the predicted result.

For example, if the probability of an earthquake occurring in the next 12 months is 50%, and the chances of it catching me in an unstable building are also 50%, the probability of both events happening at the same time decreases to 25%, i.e. the product of the first two probabilities. If we add to this that the earthquake will be strong (also a 50% probability) or that of the house collapsing (50% probability), then the risks of being caught under the rubble decrease first to 12.5% and then further to 6.25%.

This sophism can also be dismantled when we prove that some of the premises with which it operates are illogical, or show that the end result is not necessarily a negative one. In an argument like: “If you go to church, you’ll be brainwashed and end up not drinking, not smoking, not going to clubs, thus not enjoying life”, the premise of brainwashing is neither proven nor logical. Brainwashing aims to radically change the way a person thinks, so that they become a puppet, automatically executing orders received from a higher authority2, and its use has nothing to do with how a person decides to become a member of a Christian church. It is also impossible to prove that all people enjoy life in the same way, or to argue that giving up alcohol or tobacco is a negative thing (at least if we take into account the existing medical evidence).

In the case of slippery slope arguments that warn of setting a dangerous precedent, they erroneously suggest that there are only two options (either we do not set the precedent or, if we do, we are obliged to treat other cases similarly), ignoring the possibility of treating future cases differently, even if there is a precedent.

Arguments make a difference

In 1954, President Eisenhower argued for American intervention in Vietnam, arguing that once Indochina was won by the Communists, Burma, Thailand and Indonesia would also fall like dominoes. The whole of Southeast Asia would become communist. In the end, the Vietnam War proved to be one of the resounding failures of US foreign policy, and Eisenhower’s theory proved valid only in the case of Cambodia.

Using the slippery slope mechanism, valid arguments can also be constructed, says Professor Eugene Volokh3. Thus, in order to demonstrate that there can be a positive correlation between the current “public registration of gun owners” and the government’s decision to confiscate weapons in the future, Volokh presents a number of mechanisms that would make it possible to move from one decision to another. The gun registration measure could create a political impetus in favour of those who support arms control. A cumbersome arms registration procedure could discourage their acquisition, thus reducing the number of gun owners and those claiming the right to own weapons. The population could change their perception of weapons, considering their ownership a privilege granted by the government, rather than a right. Thus, the likelihood of weapon confiscation would eventually become politically feasible.

In any case, since the slippery slope argument frequently operates with probabilities, and we humans are generally not very good at assessing probabilities, we need to rigorously examine the evidence for the supposed inevitability of slipping into a negative scenario.

Even when things take an unwanted turn, we know from experience that they can stop in the middle, or return to a better trajectory. Because, although we are often wrong, we are not doomed, like Slinky toys, to only ever go down.

Enhance your critical thinking. Read more of our articles on the topic.

Carmen Lăiu is a writer for ST Network and Semnele timpului.

Slippery Slope: What It Is and How to Respond to It», Efectiviology,
Edward Hunter, Brainwashing: The Story of Men Who Defied It, Forgotten Books , 2012.
Eugene Volokh, «The Mechanisms of the Slippery Slope», în Harvard Law Review, vol. 116, nr. 4, nov. 2002,