BEING LOGICAL BY D. Q. MCLNERNY

Key Concepts: The Foundations of Clear Thought
McInerny breaks logic down into five accessible sections, moving from mental preparation to identifying common errors:

• Preparing the Mind: Logic begins with attention. Many errors occur simply because we "skim" a situation instead of perusing it. You must distinguish between objective facts (things that exist independently) and subjective facts (internal states like a headache).
• Matching Ideas to Facts: An idea is only clear if it faithfully reflects the objective world. Bad ideas are "subjective evocations" that have lost their connection to reality; being logical means constantly touching base with the originating source of your thoughts.
• The Language of Logic: Logic and language are inseparable. To be logical, you must avoid evasive, vague, or ambiguous language. For example, a word is "vague" if its referent is blurred, and "ambiguous" if it has multiple meanings without context.
• The Basic Principles:
• Identity: A thing is what it is (A is A).
• Excluded Middle: Something either exists or it does not; there is no "middle state" between being and non-being.
• Sufficient Reason: There is an explanation for everything; nothing in the physical universe is self-explanatory.
• Contradiction: It is impossible for something to both be and not be at the same time in the same respect.

• The Anatomy of Argument: Every argument requires two parts: a premise (the starting truth) and a conclusion (the result of the inferential move). A sound argument must have both true content and a valid structure.
• Identifying Illogic: The final section dissects common fallacies—like red herrings, ad hominem attacks, and straw man arguments—teaching you how to spot and dismantle them in everyday conversation.