Editing Robert Nozick (section)

===Epistemology===
In ''[[Philosophical Explanations]]'' (1981), Nozick provided novel accounts of [[knowledge]], [[free will]], [[personal identity]], the nature of [[Value (personal and cultural)|value]], and the meaning of life. He also put forward an epistemological system which attempted to deal with both the [[Gettier problem]] and those posed by [[skepticism]]. This highly influential argument eschewed [[Theory of justification|justification]] as a necessary requirement for knowledge.<ref name=Schmidtz>{{cite book |author=Schmidtz, David |title=Robert Nozick |publisher=Cambridge University Press |location=Cambridge, UK |year=2002 |isbn=0-521-00671-6 }}</ref>{{rp|ch. 7}}

Nozick gives four conditions for S's knowing that P (S=Subject / P=Proposition):

# P is true
# S believes that P
# If it were the case that (not-P), S would not believe that P
# If it were the case that P, S would believe that P

Nozick's third and fourth conditions are [[counterfactuals]]. He called this the "tracking theory" of knowledge. Nozick believed the counterfactual conditionals bring out an important aspect of our intuitive grasp of knowledge: For any given fact, the believer's method (M) must reliably track the truth despite varying relevant conditions. In this way, Nozick's theory is similar to [[reliabilism]]. Due to certain counterexamples that could otherwise be raised against these counterfactual conditions, Nozick specified that:

<ol start="3">
<li>If P weren't the case and S were to use M to arrive at a belief whether or not P, then S wouldn't believe, via M, that P.</li>
<li>If P were the case and S were to use M to arrive at a belief whether or not P, then S would believe, via M, that P.</li><ref>Keith Derose, Solving the Skeptical Problem</ref>
</ol>

A major feature of Nozick's theory of knowledge is his rejection of the  [[Deductive closure|principle of deductive closure]].  This principle states that if S knows X and S knows that X implies Y, then S knows Y.  Nozick's truth tracking conditions do not allow for the principle of deductive closure.