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counterfactual conditional / overdetermination / knowledge / Nozick: counterfactual conditionals help to exclude cases of overdetermination. - That is, cases where multiple independent causes are sufficient for themselves. - II 174 e.g. Barn facades: if there are many fakes, one should not speak of knowledge. - II 175 counterfactual conditional: shows covariance.
Philosophical Explanations Oxford 1981
The Nature of Rationality 1994