Logic 1.2

A passage only contains an argument if it purports to prove something.

Two conditions:
•Factual Claim: at least on of the statements must claim to present evidence or reasons. (Outside the domain of logic.)

•Inferential Claim: there must be a claim that the alleged evidence or reasons supports or implies something, a claim that something follows from the evidence. (Within the domain of logic.)

Inferential Claims can be either explicit or implicit. Explicit claims assert with an indicator; implicit claims assert through an inferential relationship between the evidence and the conclusion (no indicators).

•Indicator words are no guarantee of an explicit inferential claim.

•Detecting inferential relationships is part of the art of logic. Inferential
relationship

Non-Inferential Passages:
•Warnings, Advice
•Belief or Opinion
•Loosely Associated Statements
•Reports

Expository Passages: Discourse that begins with a topic sentence and develops it, but there is no argument.
•Consider the topic sentence. If it is something that it everyone already believes, then most likely it is not an argument.
Illustrations: A statement followed by a numeration of instances.

•Consider what is illustrated. If it is something that it everyone already accepts, then most likely it is not an argument.
Explanations: A report that shed light on something already accepted as fact. It attempts to explain the why, not the that.

•The greatest difficulty in distinguishing between an explanation and an argument is deciding whether or not something is accepted as fact or not.

Conditional Statements: an “if…then” statement. They are not arguments; the conditional purports neither to supply evidence, nor to draw a conclusion form any evidence. Also, within a conditional statement, neither the antecedent, nor the consequent are purported to be true. Conditional statements, however, can be used to make an argument.

•Antecedent: the statement following the “if”.
•Consequent: the statement following the “then”.
Ex.: “If Venus is the Morning Star, then Colin Powell is the president of the United States.”

Conditionals express the relationship between necessary and sufficient conditions

A is a sufficient condition for B whenever the occurrence of A is all that is needed for the occurrence of B.

B is a necessary condition for A whenever A cannot occur without the occurrence of B.