In reasoning to argue a claim, a fallacy is reasoning that is evaluated as logically incorrect and that undermines the logical validity of the argument and permits its recognition as unsound.
An important part of critical thinking is the use of logic.
-An argument is valid when the conclusion necessarily follows from the premises. Therefore, all men are women This is a valid argument, but not sound, because a premise is not true: 1. There are quite a few such fallacies, but here I offer a dozen of the more common forms: Non sequitur (Latin, “it does not follow”).
In such an argument it is logically impossible for the premises to be true and the conclusion false. Therefore, Socrates is mortal (conclusion) This is an invalid argument (the conclusion does not follow from the premises): 1. An argument is a non sequitur if the conclusion does not follow from the premise.
The conscious or habitual use of fallacies as rhetorical devices is prevalent in the desire to persuade when the focus is more on communication and eliciting common agreement rather than on the correctness of the reasoning.
The effective use of a fallacy by an orator may be considered clever, but by the same token, the reasoning of that orator should be recognized as unsound, and thus the orator's claim, supported by an unsound argument, will be regarded as unfounded and dismissed.