Illicit process

{{logicnav}}
An '''illicit process''' (abbreviated '''IP''') and its two sub-forms, the '''illicit major''' and the '''illicit minor''', is a [[logical fallacy]] in which a flawed conclusion is reached by improper distribution of the terms in the conclusion in the premises.

This fallacy is a [[syllogistic fallacy]] and a [[formal fallacy]].

==Explanation==
Distribution is really about how much of the group you're talking about. An ''undistributed'' S (subject) means you're talking about some of the group but not all of it. A ''distributed'' S means you're talking about the group as a whole. Illicit process is the fallacy that arises from drawing a deductive conclusion about the entire group based on part of the group. This means illicit process is a one-way fallacy. If we have a distributed S in the premise, we can draw an undistributed conclusion because we're drawing a conclusion about part of the group based on all of the group. But we can't draw a conclusion about all based on a few.

==Form==
An illicit process has two forms. The '''subject''' is the major term and the '''predicate''' is the minor term. Undistributed will be abbreviated '''U''' and distributed will be '''D''' but will only be put after the major or minor term to clarify what the fallacy is exactly.

===Illicit major===
{{syl
|2=All '''M'''  are '''S''' (U).
|4=Some '''P''' are not '''M'''.
|5=C|6=Some '''P''' are not '''S''' (D).
}}

Alternately:
{{syl
|2=All '''Middle''' are '''Subject''' (U).
|4=Some '''Predicate''' are not '''Middle'''.
|5=C|6=Some '''Predicate''' are not '''Subject''' (D).
}}

===Illicit minor===
{{syl
|2=All '''M''' are '''S'''.
|4=All '''M''' are '''P''' (U).
|5=C|6=All '''P''' (D) are '''S'''.
}}

Alternately:
{{syl
|2=All '''Middle''' are '''Subject'''.
|4=All '''Middle''' are '''Predicate''' (U).
|5=C|6=All '''Predicate''' (D) are '''Subject'''.
}}

==Examples==

===Illicit major===
{{syl
|2=All [[dog]]s are [[mammals]].
|4=No [[cats]] are dogs.
|5=C|6=Therefore, no cats are mammals.
}}

In this argument, the major term is "mammals". This is distributed in the conclusion (the last statement) because we are making a claim about a property of all mammals: that they are not cats. However, it is not distributed in the major premise (the first statement) where we are only talking about a property of ''some'' mammals: only some mammals are dogs.

===Illicit minor===
{{syl
|2=All cats are felines.
|4=All cats are mammals.
|5=C|6=All mammals are felines.
}}

The minor term here is mammal, which is not distributed in the minor premise "All cats are mammals," because this premise is only defining a property of possibly some mammals (i.e., that they're cats.) However, in the conclusion "All mammals are felines," mammal is distributed (it is talking about all mammals being felines). It is shown to be false by any mammal that is not a feline; for example, a dog.

===Anti-evolution===
In his critique of a [[creationist]] article on [[genetic]] recombination, Alec MacAndrew identifies several logical flaws including the illicit process of the following form:<ref>Alec MacAndrew's [http://www.evolutionpages.com/Critique%20of%20Ashcraft%20article.htm Genetic Recombination Misused], a critique of Christopher Ashcroft's [http://www.evolutionpages.com/Genetic%20Recombination%20and%20the%20Origin%20of%20New%20Information.htm A New Look at Genetic Recombination]</ref>
{{syl
|2=All recombination causes change in [[DNA]] sequences.
|4=All recombination is regulated by [[cell]]ular mechanisms.
|5=C|6=Therefore, all changes in DNA sequence are regulated by cellular mechanisms.
}}

The flaw is that, while recombination may cause change in DNA sequences, it is not proposed as causing all change in DNA sequences. However, the conclusion is about all DNA sequences. The major premise does not distribute across all DNA sequences while the conclusion does.

==Illicit observation==
An illicit observation is not an error of illicit process. It occurs when two terms that seem to be opposite (but aren't) are used as if they are opposites.

The fallacy is a combination of [[equivocation]] and a [[four-term fallacy]] and is a [[fallacy of ambiguity]].

==See also==
*[[Logical fallacy]]
*[[Syllogism]]

==External links==
*[http://www.fallacyfiles.org/illicitp.html Illicit process], [http://www.fallacyfiles.org/illmajor.html illicit major], [http://www.fallacyfiles.org/illminor.html illicit minor], [[Fallacy Files]]
*[http://philosophy.lander.edu/logic/illicit_fall.html Syllogistic fallacies], Lander University
*[http://atheism.about.com/library/FAQs/skepticism/blfaq_fall_illicit.htm Illicit Observation], Atheism/Agnosticism About.com
*[http://onegoodmove.org/fallacy/illmin.htm Illicit Minor], Stephen Downes

==References==
{{reflist}}

{{logfal}}

[[Category:Formal fallacies]]

Categories: Formal fallacies