In a slippery slope argument, a course of action is rejected because the slippery slope advocate believes it will lead to a chain reaction resulting in an undesirable end or ends. [1] The core of the slippery slope argument is that a specific decision under debate is likely to result in unintended consequences. The strength of such an argument depends on whether the small step really is likely to lead to the effect. This is quantified in terms of what is known as the warrant (in this case, a demonstration of the process that leads to the significant effect).
This type of argument is sometimes used as a form of fearmongering in which the probable consequences of a given action are exaggerated in an attempt to scare the audience.[ citation needed ] When the initial step is not demonstrably likely to result in the claimed effects, this is called the slippery slope fallacy. This is a type of informal fallacy, and is a subset of continuum fallacy, in that it ignores the possibility of middle ground and assumes a discrete transition from category A to category B. Other idioms for the slippery slope fallacy are the thin edge of the wedge, domino fallacy (as a form of domino effect argument) or dam burst, and various other terms that are sometimes considered distinct argument types or reasoning flaws, such as the camel's nose in the tent, parade of horribles , boiling frog , and snowball effect .
Some writers distinguish between a slippery slope event and a slippery slope argument. [2] [3] : 122 A slippery slope event can be represented by a series of conditional statements, namely:
The idea being that through a series of intermediate steps, p will imply z. Some writers point out that strict necessity isn't required and it can still be characterized as a slippery slope if at each stage the next step is plausible. [2] [4] : 186 With strict implication, p will imply z, but if at each step the probability is 90%, for example, then the more steps there are, the less likely it becomes that p will cause z.
A slippery slope argument is typically a negative argument where there is an attempt to discourage someone from taking a course of action because if they do it will lead to some unacceptable conclusion. [5] Some writers point out that an argument with the same structure might be used in a positive way in which someone is encouraged to take the first step because it leads to a desirable conclusion. [6]
If someone is accused of using a slippery slope argument then it is being suggested they are guilty of fallacious reasoning, and while they are claiming that p implies z, for whatever reason, this is not the case. In logic and critical thinking textbooks, slippery slopes and slippery slope arguments are normally discussed as a form of fallacy, although there may be an acknowledgement that non-fallacious forms of the argument can also exist. [7] : 273–311
Different writers have classified slippery slope arguments in different and often contradictory ways, [7] : 273–311 but there are two basic types of argument that have been described as slippery slope arguments. [8] [9] One type has been called the causal slippery slope, [10] [11] : 308 and the distinguishing feature of this type is that the various steps leading from p to z are events with each event being the cause of the next in the sequence. [12] The second type might be called the judgmental slippery slope with the idea being that the 'slope' does not consist of a series of events but is such that, for whatever reason, if a person makes one particular judgment they will rationally have to make another and so on. The judgmental type may be further sub-divided into conceptual slippery slopes and decisional slippery slopes.
Conceptual slippery slopes, which Trudy Govier calls the fallacy of slippery assimilation, [11] [13] are closely related to the sorites paradox. So, in the context of talking about slippery slopes, Merilee Salmon writes: "The slippery slope is an ancient form of reasoning. According to van Fraassen (The Scientific Image), the argument is found in Sextus Empiricus that incest is not immoral, on the grounds that 'touching your mother's big toe with your little finger is not immoral, and all the rest differs only by degree.'" [14]
Decisional slippery slopes are similar to conceptual slippery slopes in that they rely on there being a continuum with no clear dividing lines such that if you decide to accept one position or course of action then there will, either now or in the future, be no rational grounds for not accepting the next position or course of action in the sequence.
The difficulty in classifying slippery slope arguments is that there is no clear consensus in the literature as to how terminology should be used. It has been said that whilst these two fallacies "have a relationship which may justify treating them together", they are also distinct, and "the fact that they share a name is unfortunate". [8] Some writers treat them side by side but emphasize how they differ. [12] Some writers use the term slippery slope to refer to one kind of argument but not the other, but don't agree on which one, whilst others use the term to refer to both. So, for example:
The metaphor of the "slippery slope" dates back at least to Cicero's essay Laelius de Amicitia (XII.41). The title character Gaius Laelius Sapiens uses the metaphor to describe the decline of the Republic upon the impending election of Gaius Gracchus: "Affairs soon move on, for they glide readily down the path of ruin when once they have taken a start." [16]
Walton suggests Alfred Sidgwick should be credited as the first writer on informal logic to describe what would today be called a slippery slope argument. [7] : 275 Sidgwick wrote in 1910: [17]
We must not do this or that, it is often said, because if we did we should be logically bound to do something else which is plainly absurd or wrong. If we once begin to take a certain course there is no knowing where we shall be able to stop within any show of consistency; there would be no reason for stopping anywhere in particular, and we should be led on, step by step into action or opinions that we all agree to call undesirable or untrue.
Sidgwick says this is "popularly known as the objection to a thin end of a wedge" but might be classified now as a decisional slippery slope. However, the wedge metaphor also captures the idea that unpleasant end result is a wider application of a principle associated with the initial decision which is often a feature of decisional slippery slopes due to their incremental nature but may be absent from causal slippery slopes.
T. Edward Damer, in his book Attacking Faulty Reasoning , describes what others might call a causal slippery slope but says: [18] : 135
While this image may be insightful for understanding the character of the fallacy, it represents a misunderstanding of the nature of the causal relations between events. Every causal claim requires a separate argument. Hence, any "slipping" to be found is only in the clumsy thinking of the arguer, who has failed to provide sufficient evidence that one causally explained event can serve as an explanation for another event or for a series of events.
Instead Damer prefers to call it the domino fallacy. Howard Kahane suggests that the domino variation of the fallacy has gone out of fashion because it was tied to the domino theory for the United States becoming involved in the war in Vietnam and although the U.S. lost that war, "it is primarily communist dominoes that have fallen". [18] : 84
Frank Saliger notes that "in the German-speaking world the dramatic image of the dam burst seems to predominate, in English speaking circles talk is more of the slippery slope argument", [19] : 341 and that "in German writing dam burst and slippery slope arguments are treated as broadly synonymous. In particular the structural analyses of slippery slope arguments derived from English writing are largely transferred directly to the dam burst argument." [19] : 343
In exploring the differences between the two metaphors, he comments that in the dam burst the initial action is clearly in the foreground and there is a rapid movement towards the resulting events whereas in the slippery slope metaphor the downward slide has at least equal prominence to the initial action and it "conveys the impression of a slower 'step-by-step' process where the decision maker as participant slides inexorably downwards under the weight of its own successive (erroneous) decisions". [19] : 344 Despite these differences Saliger continues to treat the two metaphors as being synonymous. Walton argues that although the two are comparable "the metaphor of the dam bursting carries with it no essential element of a sequence of steps from an initial action through a gray zone with its accompanying loss of control eventuated in the ultimate outcome of the ruinous disaster. For these reasons, it seems best to propose drawing a distinction between dam burst arguments and slippery slope arguments." [15]
Eric Lode notes that: [20] : 1470
"Commentators have used numerous different metaphors to refer to arguments that have this rough form. For example, people have called such arguments "wedge" or "thin edge of the wedge", "camel's nose" or "camel's nose in the tent", "parade of horrors" or "parade of horribles", "domino", "boiling frog" and "this could snowball" arguments. All of these metaphors suggest that allowing one practice or policy could lead us to allow a series of other practices or policies."
Bruce Waller says it is lawyers who often call it the "parade of horribles" argument while politicians seem to favor "the camel's nose is in the tent". [21] : 252
The 1985 best-selling children's book If You Give a Mouse a Cookie by Laura Joffe Numeroff and Felicia Bond popularized the general idea of the slippery slope for recent generations.
Given the disagreement over what constitutes a genuine slippery slope argument, it is to be expected that there are differences in the way they are defined. Lode says that "although all SSAs share certain features, they are a family of related arguments rather than a class of arguments whose members all share the same form." [20] : 1476
Various writers [22] [23] [20] have attempted to produce a general taxonomy of these different kinds of slippery slope. Other writers have given a general definition that will encompass the diversity of slippery slope arguments. Eugene Volokh says, "I think the most useful definition of a slippery slope is one that covers all situations where decision A, which you might find appealing, ends up materially increasing the probability that others will bring about decision B, which you oppose." [24] : 1030
Those who hold that slippery slopes are causal generally give a simple definition, provide some appropriate examples and perhaps add some discussion as to the difficulty of determining whether the argument is reasonable or fallacious. Most of the more detailed analysis of slippery slopes has been done by those who hold that genuine slippery slopes are of the decisional kind.
Lode, having claimed that SSAs are not a single class of arguments whose members all share the same form, nevertheless goes on to suggest the following common features. [20]
Rizzo and Whitman identify slightly different features. They say, "Although there is no paradigm case of the slippery slope argument, there are characteristic features of all such arguments. The key components of slippery slope arguments are three: [2]
Walton notes that these three features will be common to all slippery slopes but objects that there needs to be more clarity on the nature of the 'mechanism' and a way of distinguishing between slippery slope arguments and arguments from negative consequences. [7] : 275
Corner et al. say that a slippery slope has "four distinct components:
The alleged danger lurking on the slippery slope is the fear that a presently unacceptable proposal (C) will (by any number of psychological processes—see, e.g., Volokh 2003) in the future be re-evaluated as acceptable." [25]
Walton adds the requirement that there must be a loss of control. He says, there are four basic components: [15]
One is a first step, an action or policy being considered. A second is a sequence in which this action leads to other actions. A third is a so-called gray zone or area of indeterminacy along the sequence where the agent loses control. The fourth is the catastrophic outcome at the very end of the sequence. The idea is that as soon as the agent in question takes the first step he will be impelled forward through the sequence, losing control so that in the end he will reach the catastrophic outcome. Not all of these components are typically made explicit ...."
Ad hominem, short for argumentum ad hominem, refers to several types of arguments that are fallacious. Often currently this term refers to a rhetorical strategy where the speaker attacks the character, motive, or some other attribute of the person making an argument rather than the substance of the argument itself. This avoids genuine debate by creating a diversion often using a totally irrelevant, but often highly charged attribute of the opponent's character or background. The most common form of this fallacy is "A" makes a claim of "fact", to which "B" asserts that "A" has a personal trait, quality or physical attribute that is repugnant thereby going off-topic, and hence "B" concludes that "A" has their "fact" wrong – without ever addressing the point of the debate. Many contemporary politicians routinely use ad hominem attacks, some of which can be encapsulated to a derogatory nickname for a political opponent used instead of political argumentation.
A domino effect is the cumulative effect produced when one event sets off a series of similar or related events, a form of chain reaction. The term is an analogy to a falling row of dominoes. It typically refers to a linked sequence of events where the time between successive events is relatively short. The term can be used literally or metaphorically.
A false dilemma, also referred to as false dichotomy or false binary, is an informal fallacy based on a premise that erroneously limits what options are available. The source of the fallacy lies not in an invalid form of inference but in a false premise. This premise has the form of a disjunctive claim: it asserts that one among a number of alternatives must be true. This disjunction is problematic because it oversimplifies the choice by excluding viable alternatives, presenting the viewer with only two absolute choices when, in fact, there could be many.
A straw man fallacy is the informal fallacy of refuting an argument different from the one actually under discussion, while not recognizing or acknowledging the distinction. One who engages in this fallacy is said to be "attacking a straw man".
In classical rhetoric and logic, begging the question or assuming the conclusion is an informal fallacy that occurs when an argument's premises assume the truth of the conclusion. Historically, begging the question refers to a fault in a dialectical argument in which the speaker assumes some premise that has not been demonstrated to be true. In modern usage, it has come to refer to an argument in which the premises assume the conclusion without supporting it. This makes it an example of circular reasoning.
A fallacy is the use of invalid or otherwise faulty reasoning in the construction of an argument that may appear to be well-reasoned if unnoticed. The term was introduced in the Western intellectual tradition by the Aristotelian De Sophisticis Elenchis.
Post hoc ergo propter hoc is an informal fallacy that states "Since event Y followed event X, event Y must have been caused by event X." It is a fallacy in which an event is presumed to have been caused by a closely preceding event merely on the grounds of temporal succession. This type of reasoning is fallacious because mere temporal succession does not establish a causal connection. It is often shortened simply to post hoc fallacy. A logical fallacy of the questionable cause variety, it is subtly different from the fallacy cum hoc ergo propter hoc, in which two events occur simultaneously or the chronological ordering is insignificant or unknown. Post hoc is a logical fallacy in which one event seems to be the cause of a later event because it occurred earlier.
Logical reasoning is a mental activity that aims to arrive at a conclusion in a rigorous way. It happens in the form of inferences or arguments by starting from a set of premises and reasoning to a conclusion supported by these premises. The premises and the conclusion are propositions, i.e. true or false claims about what is the case. Together, they form an argument. Logical reasoning is norm-governed in the sense that it aims to formulate correct arguments that any rational person would find convincing. The main discipline studying logical reasoning is logic.
Argumentation theory is the interdisciplinary study of how conclusions can be supported or undermined by premises through logical reasoning. With historical origins in logic, dialectic, and rhetoric, argumentation theory includes the arts and sciences of civil debate, dialogue, conversation, and persuasion. It studies rules of inference, logic, and procedural rules in both artificial and real-world settings.
Informal fallacies are a type of incorrect argument in natural language. The source of the error is not just due to the form of the argument, as is the case for formal fallacies, but can also be due to their content and context. Fallacies, despite being incorrect, usually appear to be correct and thereby can seduce people into accepting and using them. These misleading appearances are often connected to various aspects of natural language, such as ambiguous or vague expressions, or the assumption of implicit premises instead of making them explicit.
In logic and philosophy, a formal fallacy is a pattern of reasoning rendered invalid by a flaw in its logical structure that can neatly be expressed in a standard logic system, for example propositional logic. It is defined as a deductive argument that is invalid. The argument itself could have true premises, but still have a false conclusion. Thus, a formal fallacy is a fallacy in which deduction goes wrong, and is no longer a logical process. This may not affect the truth of the conclusion, since validity and truth are separate in formal logic.
Douglas Neil Walton was a Canadian academic and author, known for his books and papers on argumentation, logical fallacies and informal logic. He was a Distinguished Research Fellow of the Centre for Research in Reasoning, Argumentation, and Rhetoric (CRRAR) at the University of Windsor, Ontario, Canada, and before that (2008–2014), he held the Assumption Chair of Argumentation Studies at the University of Windsor. Walton's work has been used to better prepare legal arguments and to help develop artificial intelligence.
The following outline is provided as an overview of and topical guide to thought (thinking):
Appeal to the stone, also known as argumentum ad lapidem, is a logical fallacy that dismisses an argument as untrue or absurd. The dismissal is made by stating or reiterating that the argument is absurd, without providing further argumentation. This theory is closely tied to proof by assertion due to the lack of evidence behind the statement and its attempt to persuade without providing any evidence.
Informal logic encompasses the principles of logic and logical thought outside of a formal setting. However, the precise definition of "informal logic" is a matter of some dispute. Ralph H. Johnson and J. Anthony Blair define informal logic as "a branch of logic whose task is to develop non-formal standards, criteria, procedures for the analysis, interpretation, evaluation, criticism and construction of argumentation." This definition reflects what had been implicit in their practice and what others were doing in their informal logic texts.
Critics of euthanasia sometimes claim that legalizing any form of the practice will lead to a slippery slope effect, resulting eventually in non-voluntary or even involuntary euthanasia. The slippery slope argument has been present in the euthanasia debate since at least the 1930s.
In argumentation theory, an argumentum ad populum is a fallacious argument which is based on claiming a truth or affirming something is good or correct because many people think so.
In argumentation theory, an argumentation scheme or argument scheme is a template that represents a common type of argument used in ordinary conversation. Many different argumentation schemes have been identified. Each one has a name and presents a type of connection between premises and a conclusion in an argument, and this connection is expressed as a rule of inference. Argumentation schemes can include inferences based on different types of reasoning—deductive, inductive, abductive, probabilistic, etc.