Logical Fallacy of False Conversion / Illicit Conversion

False conversion is a formal fallacy that covers up the problem when reasoning is based on one of the three fallacies of Agrippa's trilemma. Whenever a logical fallacy is committed, the fallacy has its roots in Agrippa's trilemma. All human thought (without Divine revelation) is based on one of three unhappy possibilities. These three possibilities are infinite regress, circular reasoning, or axiomatic thinking. This problem is known as Agrippa's trilemma. Some have claimed that only logic and math can be known without Divine revelation; however, that is not true. There is no reason to trust either logic or math without Divine revelation. Science is also limited to the pragmatic because of the weakness on human reasoning, which is known as Agrippa's trilemma.

The logical fallacy of false conversion / illicit conversion occurs when the terms of a premise are switched in the conclusion when the premise uses the word all of some/not.

"All S are P. Therefore, all P are S.

No S are P. Therefore, no P are S.

Some S are P. Therefore, some P are S."

Examples of the Logical Fallacy of False Conversion / Illicit Conversion

"All S are P. Therefore, all P are S." (invalid form)

"All trucks are vehicles. Therefore, all vehicles are trucks." (invalid form)

"Some S are not P. Therefore, some P are not S." (invalid form)

"Some vehicles are not trucks. Therefore, some trucks are not vehicles." (invalid form)

If the premise uses some/are or none or no, the logical argument can reverse the terms in the conclusion and still remain valid.

"No S are P. Therefore, no P are S." (valid form)

"No trucks are sports cars. Therefore, no sports cars are trucks." (valid form)

"Some S are P. Therefore, some P are S." (valid form)

"Some men are short people. Therefore, some short people are men." (valid form)