Philosophy Stack Exchange
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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.

The following are sources of information on the syllogism.

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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, Camestres, Festino, Baroco ← second…
Geremia
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Why bother with anything else besides Aristotle's syllogistic logic?

Disclaimer: this a "devil's advocate's question", meaning I know a lot of the answer, but for the sake of playing the Q&A game, I won't self-answer right away. The main reason I'm formulating this as a question is that there are some users here…
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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 of the form: all A's are B's all A's are…
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What is the nature of "validity" in deduction when dealing with conclusions unrelated to premises?

I studying graduate math (not very far into it), and I realized that some of the higher-level math texts I would like to read are hard to understand without a strong basis in logic. Now I've taken elementary courses (like general college first year)…
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Does this syllogism by Russell show that Aristotelian logic doesn't work?

I have been reading through Hurley's A Concise Introduction to Logic, and I just finished reading the chapters about categorical syllogisms. While prodding around Wikipedia looking for some interesting reading material about Aristotelian logic, I…
Conner N. Howell
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"All men are mortal, Socrates is a man, therefore, Socrates is mortal" original quote

Where the syllogism "All men are mortal / Socrates is a man / Therefore, Socrates is mortal" first appeared?
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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, and predicate logic. Beginning with syllogistic…
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Is reduction to the absurdum to be considered a syllogism?

I was reading this article called Aristotle on the fourth figure. Thea author while exposing Aristotle theory of syllogism, identify 3 kinds of syllogisms which believes Aristotle to discuss: Ostensive (Categorical?) Syllogism Hypothetical…
Gabriele Scarlatti
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Are "All A is B" and "If A then B" always logically equivalent?

Will "All A is B" always imply "If A then B?" If so, can we say that the following follows the form of Modus Ponens? All dogs are mammals. Toby is a dog. So, Toby is a mammal. Can I rewrite the above to be: If it is a dog, it is a mammal. Toby…
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Is syllogism an inference rule?

I was reading Anthony Andres' article, "ARISTOTLE AND THE CONVENTIONAL LOGICIANS ON THE FOURTH FIGURE". The author explains why according to him the introduction of the fourth figure by his students and in today's logic books is a…
Gabriele Scarlatti
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Reverse Conclusion of Hypothetical Syllogism

I am presented with an argument of form: If p, then q. If q, then r. Therefore, if r, then p. Does this structure have a specific title? I know that it is invalid, and am assuming that "reverse hypothetical syllogism" is nowhere near correct.…
Ben
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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 hence option e.) is correct but in the book option…
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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 particular; and Man is predicated of Socrates. Is this the…
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Possible vs may (or impossible vs cannot) in Aristotle's Prior Analytics

In chapter 13 of the Prior Analytics, it is written that "it is evident if it is possible for A to apply to B, it is also possible for it not to apply". Which naively speaking makes sense, because unless something is clearly impossible, both "it is…
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Could the link between virtues and pleasures and pains in the third chapter of Nicomachean Ethics' book II be considered a hypothetical syllogism?

In the chapter 3 of Nicomachean Ethics' book II, Aristotle says: Again, if the virtues are concerned with actions and passions, and every passion and every action is accompanied by pleasure and pain, for this reason also virtue will be…
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