Questions tagged [syllogism]

A syllogism is a form of deductive reasoning described by Aristotle containing two premises and a conclusion. Each of the premises and the conclusion contain a subject and a predicate.

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help with answering the set of statements : All cats are lions, some lions are mice, all mice are giraffes

Consider the three statements A,B and C to be true even if they are different from the commonly known facts I drew two euler diagrams for this and concluded that conlusion II and IV follows and ...
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How do affirmative premises assert class inclusion rather than class separation?

Source: A Concise Introduction to Logic (12 Ed, 2014), by Patrick J. Hurley. Please observe my amelioration (and so change) of Hurley's notation; I use MIN, MAJ, and MID to abbreviate the Minor, Major,...
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Why can an affirmative conclusion never be drawn from negative premises?

Source: A Concise Introduction to Logic (12 Ed, 2014), by Patrick J. Hurley. Please observe my amelioration (and so change) of Hurley's notation. [p 287:] Rule 4: A Negative Premise Requires a ...
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In a Syllogism with an I Proposition as the conclusion, why must both premises be affirmative?

Source: A Concise Introduction to Logic (12 Ed, 2014), by Patrick J. Hurley [p 286:] Rule 1: The Middle Term Must Be Distributed at Least Once. [p 288:] Rule 4: A Negative Premise Requires a ...
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Is “only A are B” the same as “all B are A”?

I have two syllogisms which I think are pretty similar. Correct me if I am wrong but I believe "Only A are B" is the same as "All B are A". Only A are B (Can be rewritten as "All B are A") Only B are ...
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Particulars in a conditional syllogism

I have the following syllogism: Should all goods come from virtue, no evil man possesses the good. Some evil men possess the good. Therefore, some goods do not come from virtue. I ...
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What is a predicate according to Aristotle's Organon?

There is of course predicate as in predicate logic; but I'm asking about the notion in Aristotle's Organon. Consider the proposition: Socrates is a man. Man is a universal, Socrates is a ...
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Concerning the integrity of some logical syllogisms on moral subjectivism and ice-cream

I understand moral subjectivism to be the meta-ethical idea that all moral statements are merely expressions of the individual and thus that there are no moral statements that are implicitly (...
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Representation of Categorical Syllogism in Symbolic Logic

How would I represent a AAA categorical syllogism with symbolic logic?
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Why is the darapti syllogism invalid?

I found the following exposition of darapti on wikipedia: All squares are rectangles. (MaP) All squares are rhombuses. (MaS) ∴ Some rhombuses are rectangles. (SiP) As far as I can see, this is ...
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Are analogical middle terms sufficient for a valid demonstration?

William A. Wallace, O.P., in “Thomism and the Quantum Enigma,” The Thomist 61 (1997): 455–468, claims that analogical middle terms are sufficient for a valid demonstration and that this is a ...
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How do I use the “Barbara, Celarent, … etc.” mnemonic?

Medieval logicians memorized this most famous logic mnemonic: Barbara, Celarent, Darii, Ferio ← direct first figure Baralipton, Celantes, Dabitis, Fapesmo, Frisesomorum ← indirect first figure Cesare,...
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Syllogistic Logic: Negation of a Categorical Proposition?

I am beginner of logic, and am writing an introduction to logic for a math book. I am of the impression that the three main areas of logic to explain are (in order) syllogistic logic, sentential logic,...

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