#fallacy #logic #argument #debate
idea
The slippery slope argument is a logical function in which a person makes an argument that A might lead to B, and therefore rejects A altogether to prevent B.
A is generally a mild, sometimes agreeable point. B is generally a more extreme, usually consensually disapproved. A gets discarded on the grounds that B needs to be prevented.
Slippery slope arguments are usually fallacious. Overall a slippery slope introduces a false dichotomy by merging A together with B, thus presenting the choice as being (A & B) or nothing.
A slippery slope argument can be used either because of a genuine fear that A will cause B, or as a fallacious argument to discard A without having to address it directly. This second case can be used to support a polemic position without assuming the negative connotations associated with it. It can also be used to discard a debate altogether, by framing A as an unacceptable and unreasonable position through the transfer of B's negative properties to A.
There are three types of fallacious slippery slope arguments: causation, precedence and conceptual equality. A slippery slope argument can also be logically sound.
Causation
A ⇒ B
Doing A directly causes B.
When going from A to B requires a process, logic becomes fallacious by portraying this process by being marginal, effortless or inevitable.
Precedence
C ⇒ A ∴ C ⇒ B
To allow A we will create a precedent C that will facilitate and ultimately cause B.
Fallacy comes from the presumed creation of the precedent C, which will create inability to judge B differently from A in the future.
Conceptual equality
∃ C, D, ..., E / A ≃ C, C ≃ D, D ≃ ... , ... ≃ E, E ≃ B ⇒ A ≃ B
There is a series of predicates that are very close to one-another from A to B, authorizing A will cause a chain reaction leading to B.
Fallacy comes from the assumption that each of the predicates are indistinguishable, causing that chain reaction.
Logically sound argument
P(B | A) ≫ P(B | ^A)
A slippery slope argument can be sound. In this case there is a known probabilistic chain of events that will lead from A to B, and the probabilities of A leading to B are judged significantly higher than that of B without A, therefore discarding A to prevent B.
Responding to slippery slope
The argument is structured around the likely, or inevitable evolution from A to B ; therefore a response against the fallacious use of the slippery slope can be structured around the unlikelihood or preventability of this evolution:
- The origin event might be necessary but not sufficient[1]. ∃ C / (A | ^C) ⇏ B
- Highlight the improbability of a certain causality chain (refute that A ≃ C, and in fact A ≠ C)
- Illustrate the difference of state between A and B, highlighting that A and B can be dealt with independently
- Show ways to reduce the probability of transition between A and B. ∃ C / P(B | A & C) ≃ P(B | ^A)
- Find issues in the premise of the argument. <!-- @todo to be completed →
- Point the logical fallacy itself, illustrate with another ridiculous slippery slope argument
- Ask for proof.