Objection. Sensitivity violates the closure principle: I can know I have hands while not knowing I am not a handless brain in a vat.

Reply. Nozick accepts the denial of closure. The reply is that methods track different propositions differently; closure looks intuitive but may not preserve the modal relation required for knowledge. Most epistemologists judge the cost too high, which motivates safety instead.

Objection. Some true beliefs can be insensitive for harmless reasons, especially necessary truths or beliefs about one’s own methods.

Reply. This shows the simple counterfactual needs careful formulation. Sensitivity works best as a diagnostic anti-luck idea rather than an all-purpose test applied mechanically to every proposition.