Syllogism
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Syllogism
/ˈsɪləˌdʒɪzəm/
Definition
A syllogism is a logical argument composed of three parts: the major premise, the minor premise, and the conclusion inferred from the premises. I will help you to understand the syllogism you just need to follow this article step by step.
Steps
First Step
First thing that you have to know is the basic structure of syllogism. As you already know the syllogism consists of three propositions :
- major premise
- minor premise and
- conclusion
in which there appear a total of exactly three categorical terms, each of which is used exactly twice. Each of the premises has one term in common with the conclusion: the major term in the major premise, which forms the predicate of the conclusion, and the minor term in the minor premise, which forms the subject of the conclusion. The categorical term in common in the premises is called the "middle term". For instance:
Major premise: No geese are felines.
Minor premise: Some birds are geese.
Conclusion: Therefore, Some birds are not felines.
In this example you can see that "felines" is the major term and predicate of the conclusion, "bird" is the minor term and subject of the conclusion, and "geese" is the middle term.
Second Step
It is easier when you try to think of each term as representing a category. For instance "plant" is a category composed of everything that can be described as a plant.
Third Step
You can notice that each part is expressed as "Some/all/no S is/are [not] P," and have four possible variation. The universal affirmative (symbolized as A) is expressed as "all S is/are P,". The universal negative (symbolized as E) is expressed as "no S is/are P,". The particular affirmative (symbolized as I) is expressed as "some S is/are P,". The particular negative (symbolized as O) is expressed as "some S is/are not P,". This you can see in the table below:
A |All |S |are |P |universal affirmatives |All humans are mortal.
E |No |S |are |P |universal negatives |No humans are perfect.
I |Some |S |are |P |particular affirmatives |Some humans are healthy.
O |Some |S |are not |P |particular negatives |Some humans are not clever.