Converse accident
Encyclopedia
The logical fallacy of converse accident (also called reverse accident, destroying the exception, or a dicto secundum quid ad dictum simpliciter) is a deductive
fallacy that can occur in a statistical syllogism
when an exception to a generalization
is wrongly called for.
For example:
The inductive version of this fallacy is called hasty generalization
. See faulty generalization
.
This fallacy is similar to the slippery slope
, where the opposition claims that if a restricted action under debate is allowed, such as allowing people with glaucoma to use medical marijuana, then the action will by stages become acceptable in general, such as eventually everyone being allowed to use marijuana. The two arguments imply there is no difference between the exception and the rule, and in fact fallacious slippery slope arguments often use the converse accident to the contrary as the basis for the argument. However, a key difference between the two is the point and position being argued. The above argument using converse accident is an argument for full legal use of marijuana given that glaucoma patients use it. The argument based on the slippery slope argues against medicinal use of marijuana because it will lead to full use.
The opposing kind of dicto simpliciter
is accident
.
Deductive reasoning
Deductive reasoning, also called deductive logic, is reasoning which constructs or evaluates deductive arguments. Deductive arguments are attempts to show that a conclusion necessarily follows from a set of premises or hypothesis...
fallacy that can occur in a statistical syllogism
Statistical syllogism
A statistical syllogism is a non-deductive syllogism. It argues from a generalization true for the most part to a particular case .-Introduction:Statistical syllogisms may use qualifying words like "most", "frequently", "almost never", "rarely",...
when an exception to a generalization
Generalization
A generalization of a concept is an extension of the concept to less-specific criteria. It is a foundational element of logic and human reasoning. Generalizations posit the existence of a domain or set of elements, as well as one or more common characteristics shared by those elements. As such, it...
is wrongly called for.
For example:
- If we allow people with glaucomaGlaucomaGlaucoma is an eye disorder in which the optic nerve suffers damage, permanently damaging vision in the affected eye and progressing to complete blindness if untreated. It is often, but not always, associated with increased pressure of the fluid in the eye...
to use medical marijuana, then everyone should be allowed to use marijuana.
The inductive version of this fallacy is called hasty generalization
Hasty generalization
Hasty generalization is a logical fallacy of faulty generalization by reaching an inductive generalization based on insufficient evidence essentially making a hasty conclusion without considering all of the variables...
. See faulty generalization
Faulty generalization
A fallacy of defective induction reaches a conclusion from weak premises. Unlike fallacies of relevance, in fallacies of defective induction, the premises are related to the conclusions yet only weakly buttress the conclusions. A faulty generalization is thus produced...
.
This fallacy is similar to the slippery slope
Slippery slope
In debate or rhetoric, a slippery slope is a classic form of argument, arguably an informal fallacy...
, where the opposition claims that if a restricted action under debate is allowed, such as allowing people with glaucoma to use medical marijuana, then the action will by stages become acceptable in general, such as eventually everyone being allowed to use marijuana. The two arguments imply there is no difference between the exception and the rule, and in fact fallacious slippery slope arguments often use the converse accident to the contrary as the basis for the argument. However, a key difference between the two is the point and position being argued. The above argument using converse accident is an argument for full legal use of marijuana given that glaucoma patients use it. The argument based on the slippery slope argues against medicinal use of marijuana because it will lead to full use.
The opposing kind of dicto simpliciter
Dicto simpliciter
A dicto simpliciter or ad dictum simpliciter are Latin phrases for a type of logical fallacy.A dicto simpliciter fallacies are deductive fallacies that occur in statistical syllogisms...
is accident
Accident (fallacy)
The logical fallacy of accident is a deductive fallacy occurring in statistical syllogisms when an exception to a rule of thumb is ignored. It is one of the thirteen fallacies originally identified by Aristotle...
.