In
debateDebate or debating is a formal method of interactive and representational argument. Debate is a broader form of argument than logical argument, which only examine the consistency from axiom, and factual argument, which only examine what is or isn't the case or rhetoric which is technique of...
or
rhetoricRhetoric is one of the arts of using language as a means to persuade. Along with grammar and logic or dialectic, rhetoric is one of the three ancient arts of discourse. From ancient Greece to the late 19th Century, it was a central part of Western education, filling the need to train public...
, a
slippery slope (also the
thin end of the wedge, sometimes misstated as
thin edge of the wedge, or the
camel's noseThe camel's nose is a metaphor for a situation where permitting some small undesirable situation will allow gradual and unavoidable worsening. A typical usage is this, from U.S. Senator Barry Goldwater in 1958:...
) is a classical
informal fallacyAn informal fallacy is an argument whose stated premises fail to support their proposed conclusion. The deviation in an informal fallacy often stems from a flaw in the path of reasoning that links the premises to the conclusion...
. A slippery slope argument states that a relatively small first step inevitably leads to a chain of related events culminating in some significant impact, much like an object given a small push over the edge of a slope sliding all the way to the bottom.
In
debateDebate or debating is a formal method of interactive and representational argument. Debate is a broader form of argument than logical argument, which only examine the consistency from axiom, and factual argument, which only examine what is or isn't the case or rhetoric which is technique of...
or
rhetoricRhetoric is one of the arts of using language as a means to persuade. Along with grammar and logic or dialectic, rhetoric is one of the three ancient arts of discourse. From ancient Greece to the late 19th Century, it was a central part of Western education, filling the need to train public...
, a
slippery slope (also the
thin end of the wedge, sometimes misstated as
thin edge of the wedge, or the
camel's noseThe camel's nose is a metaphor for a situation where permitting some small undesirable situation will allow gradual and unavoidable worsening. A typical usage is this, from U.S. Senator Barry Goldwater in 1958:...
) is a classical
informal fallacyAn informal fallacy is an argument whose stated premises fail to support their proposed conclusion. The deviation in an informal fallacy often stems from a flaw in the path of reasoning that links the premises to the conclusion...
. A slippery slope argument states that a relatively small first step inevitably leads to a chain of related events culminating in some significant impact, much like an object given a small push over the edge of a slope sliding all the way to the bottom. The fallacious sense of "slippery slope" is often used synonymously with
continuum fallacyThe continuum fallacy is an informal logical fallacy closely related to the sorites paradox, or paradox of the heap...
, in that it ignores the possibility of middle ground and assumes a discrete transition from category A to category B.
Slippery slope arguments
The argument takes on one of various semantical forms:
- In the classical form, the arguer suggests that making a move in a particular direction starts something on a path down a "slippery slope". Having started down the metaphorical slope, it will continue to slide in the same direction (the arguer usually sees the direction as a negative direction, hence the "sliding downwards" metaphor
A metaphor is a figure of speech concisely comparing two things, saying that one is the other. The English metaphor derives from the 16th c...
).
- Modern usage includes a logically valid form, in which a minor action causes a significant impact through a long chain of logical relationships. Note that establishing this chain of logical implication (or quantifying the relevant probabilities) makes this form logically valid. The slippery slope argument remains a fallacy if such a chain is not established.
Examples
Eugene VolokhEugene Volokh is an American legal commentator and law professor at the UCLA School of Law...
's
Mechanisms of the Slippery Slope (
PDF version) analyzes various types of such slippage. Volokh uses the example "gun registration may lead to gun confiscation" to describe six types of slippage (it should be noted that Volokh ignores the historical precedent that the argument is based on):
- Cost-lowering: Once all gun-owners have registered their firearms, the government will know exactly from whom to confiscate them.
- Legal rule combination: Previously the government might need to search every house to confiscate guns, and such a search would violate the Fourth Amendment to the United States Constitution
The Fourth Amendment to the United States Constitution is the part of the Bill of Rights which guards against unreasonable searches and seizures. It was ratified as a response to the abuse of the writ of assistance, which is a type of general search warrant, in the American Revolution...
. Registration would eliminate that problem.
- Attitude altering: People may begin to think of gun ownership as a privilege rather than a right, and thus regard gun confiscation less seriously.
- Small change tolerance, colloquially referred to as the "boiling frog
The boiling frog story is a widespread anecdote describing a frog slowly being boiled alive. The premise is that if a frog is placed in boiling water, it will jump out, but if it is placed in cold water that is slowly heated, it will not perceive the danger and will be cooked to death...
": People may ignore gun registration because it constitutes just a small change, but when combined with other small changes, it could lead to the equivalent of confiscation.
- Political power: The hassle of registration may reduce the number of gun owners, and thus the political power of the gun-ownership bloc.
- Political momentum: Once the government has passed this gun law it becomes easier to pass other gun laws, including laws like confiscation.
Slippery slope can also be used as a retort to the establishment of arbitrary boundaries or limitations. For example, one might argue that rent prices must be kept to $1,000 or less a month to be affordable to tenants in an area of a city. A retort invoking the slippery slope could go in two different directions:
- Once such price ceiling
A price ceiling is a government-imposed limit on how high a price can be charged on a product. Price ceilings are often intended to protect consumers from certain conditions that could make necessities unattainable. But they can also cause problems if they are used for a prolonged period of time...
s become accepted, they could be slowly lowered, eventually driving out the landlords and worsening the problem.
- If a $1,000 monthly rent is affordable, why isn't $1,025 or $1,050? By lumping the tenants into one abstract entity, the argument renders itself vulnerable to a slippery slope argument. A more careful argument in favor of price ceilings would statistically characterize the number of tenants who can afford housing at various levels based on income and choose a ceiling that achieves a specific goal, such as housing 80% of the working families in the area.
Sometimes a single action does indeed induce similar latter action. For example, judiciary decisions may set legal precedents.
The slippery slope as fallacy
The heart of the slippery slope fallacy lies in abusing the intuitively appreciable transitivity of implication, claiming that A lead to B, B leads to C, C leads to D and so on, until one finally claims that A leads to Z. While this is formally valid when the premises are taken as a given, each of those contingencies needs to be factually established before the relevant conclusion can be drawn. Slippery slope fallacies occur when this is not done — an argument that supports the relevant premises is not fallacious and thus isn't a slippery slope fallacy.
Often proponents of a "slippery slope" contention propose a long series of intermediate events as the mechanism of connection leading from A to B. The "camel's nose" provides one example of this: once a camel has managed to place its nose within a tent, the rest of the camel will inevitably follow. In this sense the slippery slope resembles the
genetic fallacyThe genetic fallacy is a fallacy of irrelevance where a conclusion is suggested based solely on something or someone's origin rather than its current meaning or context. This overlooks any difference to be found in the present situation, typically transferring the positive or negative esteem from...
, but in reverse.
As an example of how an appealing slippery slope argument can be unsound, suppose that whenever a tree falls down, it has a 95% chance of knocking over another tree. We might conclude that soon a great many trees would fall, but this is not the case. There is a 5% chance that no more trees will fall, a 4.75% chance that exactly one more tree will fall (and thus a 9.75% chance of 1 or less additional trees falling), and so on. There is a 92.3% chance that 50 or fewer additional trees will fall. The expected value of trees that will fall is 20. In the absence of some momentum factor that makes later trees more likely to fall than earlier ones, this "
domino effectThe domino effect is a chain reaction that occurs when a small change causes a similar change nearby, which then will cause another similar change, and so on in linear sequence. The term is best known as a mechanical effect, and is used as an analogy to a falling row of dominoes...
" approaches zero probability.
This form of argument often provides evaluative judgments on
social changeSocial development redirects here. For the aspect of human biological development, see psychosocial developmentSocial change is a general term which refers to:...
: once an exception is made to some rule, nothing will hold back further, more egregious exceptions to that rule.
Note that these arguments may indeed have
validityThe term Validity in logic applies to arguments or statements.-Validity of arguments:An argument is valid if and only if the truth of its premises entails the truth of its conclusion. It would be self-contradictory to affirm the premises and deny the conclusion...
, but they require some independent justification of the connection between their terms: otherwise the argument (as a logical tool) remains fallacious.
The "slippery slope" approach may also relate to the
conjunction fallacyThe conjunction fallacy is a logical fallacy that occurs when it is assumed that specific conditions are more probable than a single general one.The most oft-cited example of this fallacy originated with Amos Tversky and Daniel Kahneman:...
: with a long string of steps leading to an undesirable conclusion, the chance of
all the steps actually occurring in sequence is less than the chance of any one of the individual steps occurring alone.
Supporting analogies
Several common analogies support slippery slope arguments. Among these are analogies to physical momentum, to frictional forces and to mathematical induction.
Momentum or frictional analogies
In the momentum analogy, the occurrence of event A will initiate a process which will lead inevitably to occurrence of event B. The process may involve causal relationships between intermediate events, but in any case the slippery slope schema depends for its
soundnessIn mathematical logic, a logical system has the soundness property if and only if its inference rules prove only formulas that are valid with respect to its semantics. In most cases, this comes down to its rules having the property of preserving truth, but this is not the case in general. The word...
on the validity of some analogue for the physical principle of
momentumIn classical mechanics, momentum is the product of the mass and velocity of an object . For more accurate measures of momentum, see the section "modern definitions of momentum" on this page...
. This may take the form of a
domino theoryThe domino theory was a foreign policy theory during the 1950s to 1980s, promoted at times by the government of the United States, that speculated that if one land in a region came under the influence of communism, then the surrounding countries would follow in a domino effect...
or
contagion formulation. The domino theory principle may indeed explain why a chain of dominos collapses, but an independent argument is necessary to explain why a similar principle would hold in other circumstances.
An analogy similar to the momentum analogy is based on friction. In
physicsPhysics is a natural science; it is the study of matter and its motion through spacetime and all that derives from these, such as energy and force...
, the static co-efficient of friction is always greater than the kinetic co-efficient, meaning that it takes more force to make an object start sliding than to keep it sliding. Arguments that use this analogy assume that people's habits or inhibitions act in the same way. If a particular rule A is considered inviolable, some force akin to static friction is regarded as maintaining the status quo, preventing movement in the direction of abrogating A. If, on the other hand, an exception is made to A, the countervailing resistive force is akin to the weaker kinetic frictional force. Validity of this analogy requires an argument showing that the initial changes actually make further change in the direction of abrogating A easier.
Induction analogy
Another analogy resembles
mathematical inductionMathematical induction is a method of mathematical proof typically used to establish that a given statement is true of all natural numbers. It is done by proving that the first statement in the infinite sequence of statements is true, and then proving that if any one statement in the infinite...
. Consider the context of evaluating each one of a class of events A
1, A
2, A
3,..., A
n (for example, is the occurrence of the event harmful or not?). We assume that for each
k, the event A
k is similar to A
k+1, so that A
k has the same evaluation as A
k+1.
Therefore every A
n has the same evaluation as A
'1.
For example, the following arguments fit the slippery slope scheme with the inductive interpretation
- If we grant a building permit to build a religious structure in our community, then there will be no bound on the number of building permits we will have to grant for religious structures and the nature of this city will change. This argument instantiates the slippery slope scheme as follows: Ak is the situation in which k building permits are issued. One first argues that the situation of k permits is not significantly different from the one with k + 1 permits. Moreover, issuing permits to build 1000 religious structures in a city of 300,000 will clearly change the nature of the community.
In most real-world applications such as the one above, the naïve inductive analogy is flawed because each building permit will not be evaluated the same way (for example, the more religious structures in a community, the less likely a permit will be granted for another).
See also
- Argument from setting a precedent
Argument from precedent is a common fallacy in discussion, for example on committees or in meetings. It consists in saying that to act correctly in circumstances X would be inadvisable, in case others consider that this would set a precedent for acting in circumstances Y, where X and Y are...
- Camel's nose
The camel's nose is a metaphor for a situation where permitting some small undesirable situation will allow gradual and unavoidable worsening. A typical usage is this, from U.S. Senator Barry Goldwater in 1958:...
- Domino theory
The domino theory was a foreign policy theory during the 1950s to 1980s, promoted at times by the government of the United States, that speculated that if one land in a region came under the influence of communism, then the surrounding countries would follow in a domino effect...
- First they came...
"First they came ..." is a popular poem attributed to Pastor Martin Niemöller about the inactivity of German intellectuals following the Nazi rise to power and the purging of their chosen targets, group after group...
- Foot-in-the-door technique
Foot-in-the-door technique is a compliance tactic that involves getting a person to agree to a large request by first setting them up by having that person agree to a modest request.-Classic FITD experiments:...
- Legal precedent
- Parade of horribles
-As a literal parade:"Parade of horribles" originally referred to a literal parade of people wearing comic and grotesque costumes, rather like the Philadelphia Mummers Parade. It was a traditional feature of Fourth of July parades in parts of the U. S. in the nineteenth century, and "Horribles...
External links