Logic 101 for Honest Conversation
What rules does every good argument — from any side — actually follow?
Why it matters
Most disagreements turn less on deep disputes and more on sloppy reasoning: ambiguous terms, hidden premises, and fallacies both sides deploy. Mastering a short list of principles drastically improves the quality of conversations, and protects you from bad Christian arguments as well as bad skeptical ones.
The main case
Classical logic rests on three laws (identity: A is A; non-contradiction: not both A and not-A at the same time in the same sense; excluded middle: either A or not-A). Good arguments have a valid form (the conclusion follows if the premises are true) and sound premises (the premises actually are true). Common fallacies to learn include ad hominem, straw man, genetic fallacy, appeal to authority/popularity, and false dichotomy. A disciplined apologist should be able to diagnose these in their own arguments first.
Claim · Evidence · Objection · Response
1.The three classical laws of thought are not negotiable.
Widely acceptedEvidence
- Non-contradiction underlies all rational discourse; denying it asserts it (to deny it one must exclude its opposite).
- All known scientific reasoning presupposes these laws.
- Eastern "both/and" systems still rely on these laws when doing anything specific (arithmetic, navigation).
Strongest objection
"Quantum mechanics violates non-contradiction."
Response
Quantum systems are counterintuitive but not contradictory. A particle being in a superposition is not the same particle being in definite state X and definite state not-X simultaneously.
- Scaling the Secular City — J.P. Moreland (1987)scholarlyFind on Amazon
- Reasonable Faith — William Lane Craig (2008 (3rd ed.))scholarlyFind on Amazon
2.Fallacies often travel in both Christian and skeptical circles.
Widely acceptedEvidence
- Genetic fallacy: "you only believe that because you were raised that way" (applies equally to everyone).
- Ad hominem: "Dawkins has no theology degree" (does not address his arguments).
- Straw man: "Christians believe the earth is 6,000 years old" (sometimes; often not).
- False dichotomy: "either science or religion."
Strongest objection
"Calling out fallacies is itself a rhetorical trick."
Response
Correctly identifying a fallacy is a diagnosis, not a rebuttal. You still have to engage the underlying substantive issue.
- Tactics: A Game Plan for Discussing Your Christian Convictions — Greg Koukl (2009 (rev. 2019))popularFind on Amazon
- Reasonable Faith — William Lane Craig (2008 (3rd ed.))scholarlyFind on Amazon
What scholars debate
Formal logic is uncontroversial; informal-logic diagnoses (what counts as a fallacy in context) require judgment. Most working philosophers treat the classical laws as foundational.
Reflection
- 1.When have you made (or encountered) a genetic fallacy in the last week?
- 2.Can you name the last argument you changed your mind on — and why?
- 3.What is one Christian argument you find weak? Why?
Key sources
- Scaling the Secular City — J.P. Moreland (1987)scholarlyFind on Amazon
- Reasonable Faith — William Lane Craig (2008 (3rd ed.))scholarlyFind on Amazon
- Tactics: A Game Plan for Discussing Your Christian Convictions — Greg Koukl (2009 (rev. 2019))popularFind on Amazon
Featured thinkers
Analytic philosopher who has written on consciousness, substance dualism, naturalism, and Christian epistemology.
Apologist and communicator focused on tactics for everyday conversations — the Columbo approach of leading with questions rather than pronouncements.
A leading contemporary defender of the Kalam cosmological argument and the historicity of the resurrection.
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