The fallacy of exclusive premises is a

syllogistic fallacy A syllogism (, ''syllogismos'', 'conclusion, inference') is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true. In its earliest form (define ...

committed in a

categorical syllogism A syllogism (, ''syllogismos'', 'conclusion, inference') is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true. In its earliest form (define ...

that is invalid because both of its

premise A premise or premiss is a proposition—a true or false declarative statement—used in an argument to prove the truth of another proposition called the conclusion. Arguments consist of a set of premises and a conclusion. An argument is meaningf ...

s are negative.Goodman, Michael F. First Logic. Lanham: U of America, 1993. Web. Example of an EOO-4 type invalid syllogism :E Proposition: No

cats The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

are

dogs The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers ...

. :O Proposition: Some

are not

pets A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive/ cute appearances, int ...

. :O Proposition: Therefore, some

are not

. Explanation of Example 1: :This may seem like a logical conclusion, as it appears to be logically derived that if Some dogs are not pets, then surely some are pets, otherwise, the premise would have stated "No Dogs are pets", and if some pets are dogs, then not all pets can be cats, thus, some pets are not cats. But if this assumption is applied to the final statement then we have drawn the conclusion: some pets are cats. But this is not supported by either premise. Cats not being dogs, and the state of dogs as either pets or not, has nothing to do with whether cats are pets. Two negative premises cannot give a logical foundation for a conclusion, as they will invariably be independent statements that cannot be directly related, thus the name 'Exclusive Premises'. It is made more clear when the subjects in the argument are more clearly unrelated such as the following: Additional Example of an EOO-4 invalid syllogism :E Proposition: No

planets A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the te ...

are

. :O Proposition: Some

are not

. :O Proposition: Therefore, some

are not

. Explanation of Example 2: :In this example we can more clearly see that the physical difference between a dog and a planet is not causally linked to the domestication of dogs. The two premises are exclusive and the subsequent conclusion is nonsense, as the transpose would imply that some pets are planets. Conclusion: :The

verisimilitude In philosophy, verisimilitude (or truthlikeness) is the notion that some propositions are closer to being true than other propositions. The problem of verisimilitude is the problem of articulating what it takes for one false theory to be close ...

of the final statement is not relevant in this fallacy. The conclusions in both examples are uncontroversial; however, both are argued on fallacious logic and would not hold up as valid arguments.

References

External links

Syllogistic Fallacies: Exclusive Premises

{{Formal fallacy Syllogistic fallacies

See also

References

External links