Full Idea
The causal theory of justification was soon replaced by Nozick's construal of knowledge as counterfactually sensitive to its truth value (that is, it tracks truth). A counterfactual theory of causation connects this to the causal theory.
Gist of Idea
With a counterfactual account of the causal theory, we get knowledge as tracking or sensitive to truth
Source
Hamid Vahid (Externalism/Internalism [2011], 3)
Book Reference
'Routledge Companion to Epistemology', ed/tr. Bernecker,S/Pritchard,D [Routledge 2014], p.150
A Reaction
This is presented as an externalist theory, close to the causal theory (and prior to the reliability theory). But how could you be 'sensitive' to a changing truth if the justification was all external? Externally supported beliefs seem ossified.