Modal and Intensional Logic·Rules·Lesson 4 of 5

Counterfactuals and Possible Worlds

Introduces the Lewis-Stalnaker nearness semantics for counterfactual conditionals, distinguishes 'would' from 'might' conditionals, and explains why counterfactuals resist strengthening the antecedent.

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In this lesson · 4 sections · 2 worked examples · 4 practice activities

Counterfactuals ask about nearby alternative worlds
Would versus might counterfactuals
Why strengthening the antecedent fails
Reading counterfactuals off a simple diagram

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