Common Logical Fallacies and Learning to Develop a Graduates Perspective

Common Logical Fallacies and Learning to Develop a Graduates Perspective

Common Logical Fallacies

In logic, a fallacy is an invalid argument, that is, one in which it is possible for all the premises to be true and yet the conclusion is false. As such, it is clearly to be avoided. People often use the term colloquially, to include arguments they consider 'false' because they disagree with one or other of the premises. 'It is a fallacy that paying people the dole encourages laziness' is probably a critique of the following informal argument: 'If people can get money without working then they will become lazy (Douglas, 1989). The dole is a form of getting money without having to work for it; so, the dole encourages laziness.'

The form obtained from a proposition, a set of propositions, or an argument by abstracting from the subject matter of its content terms or by regarding the content terms as mere placeholders or blanks in a form. In a logically perfect language the logical form of a proposition, a set of propositions, or an argument is determined by the grammatical form of the sentence, the set of sentences, or the argument-text expressing it. Two sentences, sets of sentences, or argument-texts are said to have the same grammatical form, in this sense, if a uniform one-to-one substitution of content words transforms the one exactly into the other (Frans, 2009).

The sentence 'Abe properly respects every agent who respects himself' may be regarded as having the same grammatical form as the sentence 'Ben generously assists every patient who assists himself'. Substitutions used to determine sameness of grammatical form cannot involve change of form words such as 'every', 'no', 'some', 'is', etc., and they must be category-preserving, i.e., they must put a proper name for a proper name, an adverb for an adverb, a transitive verb for a transitive verb, and so on. Two sentences having the same grammatical form have exactly the same form words distributed in exactly the same pattern; and although they of course need not, and usually do not, have the same content words, they do have exactly the same number of content words (Douglas, 1989). The most distinctive feature of form words, which are also called syncategorematic terms or logical terms, is their topic neutrality; the form words in a sentence are entirely independent of and are ...