Rule 1: In a valid categorical syllogism, the middle term must be distributed in at least one premise. Rule 2: In a valid categorical syllogism, any term that is distributed in the conclusion must be distributed in the premises.

Rules of Syllogism

• Rule One: There must be three terms: the major premise, the minor premise, and the conclusion – no more, no less.
• Rule Two: The minor premise must be distributed in at least one other premise.
• Rule Three: Any terms distributed in the conclusion must be distributed in the relevant premise.

If both premises are affirmative, the conclusion must be affirmative. The reason for this rule is that affirmative premises either unite the minor and major terms, or else do not bring them into relationship with one another at all—as when there is an undistributed middle.

VALIDITY REQUIREMENT FOR THE CATEGORICAL ARGUMENT The argument must have exactly three terms. Every term must be used exactly twice. A term may be used only once in any premise. The middle term of a syllogism must be used in an unqualified or universal sense.

The Existential Fallacy is, in this regard, a little like the informal fallacy called “Equivocation.” Equivocation can cause an argument with a valid syllogistic form to be invalid; it can’t make the form itself invalid, but that particular instance or instantiation of the form can be invalid.

A deductive argument is said to be valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. Otherwise, a deductive argument is said to be invalid.

A valid syllogism is one in which the conclu- sion must be true when each of the two premises is true; an invalid syllogism is one in which the conclusions must be false when each of the two premises is true; a neither valid nor invalid syllogism is one in which the conclusion either can be true or can be false when …

A false premise is an incorrect proposition that forms the basis of an argument or syllogism. Since the premise (proposition, or assumption) is not correct, the conclusion drawn may be in error. For example, consider this syllogism, which involves a false premise: If the streets are wet, it has rained recently.

A fallacy is reasoning that is logically incorrect, undermines the logical validity of an argument, or is recognized as unsound. All forms of human communication can contain fallacies.

– Beliefs, Opinions, Assumptions become our Truths. We all have unique and individual experiences, yet we expect each other to think, act, and respond in the same way that we would. These false assumptions get us into trouble when we think others must behave in the same manner as we do, or their behavior is wrong.

Making false assumptions causes us to become less grounded in reality and more prone to creating problems for ourselves and others. To stop making assumptions and base our understanding on tangible facts, Dr.

4. An invalid deductive argument can have all false premises and a true conclusion.

All valid arguments have all true premises and true conclusions. If an argument is valid, then it must have at least one true premise. Every valid argument is a sound argument. The following is a valid deductive argument: If it snows, then we will go sledding, just like when we were kids.