FORMAL VALIDITY REVIEW

This page reviews the logical requirements for an argument to be formally valid. It does not contain explanations for any of the concepts, so you should be sure to read some material on formal validity before you take the tests.

FORMAL VALIDITY concerns how well an argument conforms to the rules of logic to arrive at a conclusion that must be true, assuming the premises are true.

MATERIAL TRUTH concerns whether or not the conclusion of an argument is true, at least to the extent that truth can be determined. If the premises are true and the argument is formally valid the conclusion will be materially true. However, depending on how the argument is constructed, the conclusion may be materially true even if the premises are false and the logic is invalid.

Formal validity and material truth are **NOT ** the same thing.

**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 middle term of an enthymeme may be used in a qualified or non-universal sense.
- A term may be distributed in the conclusion only if it has been distributed in the major or minor premise.
- At least one of the premises must be stated in the affirmative.
- If one premise is negative, the conclusion must be negative.

**VALIDITY REQUIREMENT FOR THE DISJUNCTIVE ARGUMENT **

- The minor premise must accept one alternative in the major premise, or reject all but one alternative.
- If the minor premise accepts one alternative, the conclusion must reject all other alternatives.
- If the minor premise rejects all but one alternative, the conclusion must accept the remaining alternative.

**VALIDITY REQUIREMENTS FOR THE CONDITIONAL OR HYPOTHETICAL ARGUMENT **

- The minor premise must either affirm the antecedent or deny the consequent.
- If the minor premise affirms the antecedent the conclusion must affirm the consequent.
- If the minor premise denies the consequent the conclusion must deny the antecedent.

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