Brain

Reasoning Process

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Syllogisms

Human thinking is progressive, moving from one idea to a concluding idea. Classically, there are three premises in this type of thinking process called:

Major Premise
Minor Premise
Conclusion

Major premise	The Elmo® sitting in the toy store window has an orange nose.
Minor premise	The mold for the layout of Elmo is copyrighted with a specific design pattern by Jim Hanson Productions, Inc.
Conclusion	All Elmos sold in all toy store have orange noses.

In the above, the idea in the middle premise (minor premise) helps move logically from the idea in the first premise (major premise) to the conclusion. Even though the conclusion may be true, if there be no movement from the first premise through the idea in the second premise, there is no logical flow (thought process). This lack of process is what is used in faulty logic (deception and other forms discussed later).

Picture the premises as Premise X, Premise Y, and Premise Z.

X is the major. X's set is contained in Y's set (minor premise). Z (conclusion) contains logically both Y and X.

There are three types of syllogisms:

Categorical - X is Y
fitting objects into classes; classifying objects;
Disjunctive - Either X or Y
Hypothetical - If X then Y

There are two types of reasoning: inductive and deductive. Syllogisms are used in deductive reasoning. Deductive reasoning starts with a cause and reasons to the effect. In deductive logic we reason to particular conclusions from general statements. Deduction is called reasoning a priori, which comes from Latin, meaning to look at the facts first. Inductive reasoning is a posteriori, again from Latin, meaning after seeing the evidence.

The following table illustrates the differences between deductive and inductive reasoning processes:

DEDUCTION	INDUCTION
reasons from a cause to effect	reasons for effect to cause
reasons from general to particular	reasons from particular to general
can reason from general to general	can reason from particular to particular
uses a priori reasoning	uses a posteriori reasoning
reasons to a necessary conclusion	reasons to a probable conclusion
used in philosophical reasoning	used in scientific reasoning

If the propositions in premises refer to a part of the set or class, than the object (subject) is particular. Universal propositions include all the objects of a class.

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