Inconsistent triad

An inconsistent triad is a set of three propositions that cannot all be true together. For example, 'She was an orphan; Tim outlived her; Tim was her father'.^[1]

All inconsistent triads lead to trilemmas:

• If A and B are true, C must be false.
• If A and C are true, B must be false.
• If B and C are true, A must be false.^[2]

Epistemology

Main article: Epistemology

1. Knowledge is justified true belief.^[3]
2. Humans cannot provide justification for their beliefs.^[4]
3. Humans possess knowledge.^[5]

Political philosophy

Main article: Political philosophy

1. A just society maximizes individual liberty.^[6]
2. A just society maximizes material equality.^[7]
3. A just society cannot maximize both liberty and equality.^[8]

Ethics

Main article: Ethics

1. Actions that maximize overall well-being are morally right.^[9]
2. Lying can sometimes maximize overall well-being.^[10]
3. Lying is always morally wrong.^[11]

See also

• Classical logic
• Contradiction
• Dilemma
• Formal logic
• Reductio ad absurdum
• Trilemma