Outline of Nozick's "Knowledge"

SYNOPSIS:

Robert Nozick argues that S knows that p if and only if:

(1) p is true.

(2) S believes that p.

(3) If p weren’t true, S wouldn’t believe that p.

(4) If p were true, S would believe that p and not-(S believes that not-p).

When (3) and (4) hold, S’s belief is said to “track the truth”.

OUTLINE:

Step 1: Nozick begins by impugning the standard causal account of knowledge.

Argument: The causal theory suffers from at least two weakness: (i) It fails to apply to cases of mathematical and ethical knowledge. (ii) It faces difficulties in specifying the appropriate type of causal connection.  For example, consider the case of an envatted brain that is caused (via direct electro-chemical stimulation) to have the belief that it is in a vat. Such a brain would not know it is in a vat even though the fact that it is envatted is causally connected to the belief that it is.

Upshot: We need to replace the causal requirement with a knew condition for knowledge.

Step 2: Nozick introduces a third requirement for knowledge which he thinks immunizes it from Gettier counterexamples.

Argument: Suppose S believes that (p):“someone in the office owns a Ford” based on his belief that Brown owns a Ford, when it is in fact someone else in the office, Jones, that owns a Ford, and not Brown.  S would fail to satisfy the subjunctive conditional: “If p weren’t true, S wouldn’t  believe that p”, since he would continue to believe (p) even if Jones did not own a Ford.

Upshot: We can avoid Gettier counter-examples if we adopt the following subjunctive conditional as a necessary condition for knowledge: “If p weren’t true, S wouldn’t believe that p”.

                           

Step 3: Nozick claims that the preceding subjunctive conditional illuminates difficulties relating to the “relevant alternatives” analysis of knowledge.

Argument: Compare an agent driving through a country side with only real barns and one driving through a countryside with mostly fake barns and one real barn. If both formed the true belief that he was looking at a barn, the relevant alternative analysis suggests that, given that the latter is unable to rule out the possibility that he is looking at a fake barn, only the former has knowledge. We can make sense of this by noting that if the second agent were looking at a fake barn, he would believe it was real.  He therefore fails to fulfil the preceding subjunctive conditional. 

Upshot: We can make sense of why an agent lacks knowledge when he is unable to rule out relevant alternatives if we adopt the following necessary condition for knowledge:  “If p weren’t true, S wouldn’t believe that p”.

Step 4: Nozick concedes that the preceding subjunctive conditional is not sufficient for knowledge.

Argument:  Since the envatted brain, in our previous example, is caused to believe it is in a vat by those who put it in a vat, it would not believe that it was in a vat if it were not envatted.  The envatted brain therefore fulfils the preceding subjunctive conditional.

Upshot: The subjunctive conditional, “If p weren’t true, S wouldn’t believe that p”, is not sufficient for knowledge because it does not guarantee that S’s belief is sensitive to the truth.

Step 5: Nozick introduces a second subjunctive conditional in order to make sense of why the envatted brain does not know it is in a vat.

Argument: If the envatted brain were not electrically stimulated to believe that it was in a vat by its envatters, it would not believe it was in a vat even if it remained true that it was in a vat.  Hence, the following counterfactual is not true of the envatted brain: “If p were true, S would believe that p”.

Upshot: We can accommodate the intuition that the envatted brain lacks knowledge if we adopt the following necessary condition for knowledge: “If p were true, S would believe that p”.

Step 6: Nozick argues that his second subjunctive conditional can handle Gilbert Harman’s dictator example.

Argument: A newspaper reports, truly, that a dictator has been killed, but later, falsely, denies the story. Everyone comes to believe the false report, except for S, who read the original story but failed to learn about the retraction.  Given the assumption that S would have believed the false report had he read it, Harman claims that S does not know that the dictator has been killed. Nozick’s second subjunctive conditional is able to preserve this intuition: Since S would have believed the false report, it is not the case that if it were true that the dictator was killed, S would believe that the dictator was killed.

Upshot:  Nozick’s second subjunctive conditional allows us to preserve the intuition that the subject in Harman’s dictator example lacks knowledge.

Step 7: Nozick observes that the sceptic may be seen as denying that we fulfil Nozick’s first subjunctive conditional.

Argument: If we were all envatted brains or deceived by an evil demon, we would continue to believe as we do.  Thus, the sceptic may argue that one of the following two claims is true of us: “If p were false, we wouldn’t believe that p” or “If p were false, we might believe that p”. Either would entail that we fail to satisfy the following subjunctive conditional: “If p were false, S wouldn’t believe that p.”

Upshot: According to the sceptic, we do not have knowledge because we fail to satisfy Nozick’s first subjunctive conditional.

Step 8: Nozick maintains that sceptical scenarios (henceforth, SK) are not in the not-p neighbourhood of the actual world, and therefore do not prevent us from satisfying his first subjunctive conditional.

Argument: Even if p were false, it would not be true that SK.  This is because there are no not-p worlds, in the neighbourhood of the actual world, where SK obtains. Consequently, the fact that S would continue to believe p if SK obtained, does not prevent S from fulfilling the subjunctive conditional, “If p were false, S wouldn’t believe that p”. 

Upshot: Sceptical scenarios do not prevent us from satisfying Nozick’s first subjunctive conditional.

Step 9: Nozick concedes that the sceptic is right when she insists that we do not know that not-SK.

Argument: Given that Nozick’s first subjunctive conditional is necessary for knowledge, S can know that he is not a brain in a vat only if the following were true: If S were a brain in a vat, he would not believe he was not a brain in a vat.  However, since S would still believe he was not a brain in a vat even if he were a brain in a vat, his belief does not satisfy Nozick’s first subjunctive conditional. 

Upshot: Given that we would believe that we were not brains in a vat even if we were, we do not know that we are not brains in a vat. 

Step 10: Nozick argues that acknowledging that the sceptic is right when she says that we do not know not-SK does note entail that we do not know things that entail the denial of SK. 

Argument: It does not follow that if S knows that p: “I am awake and sitting in a chair in Jerusalem” and knows that p logically implies q: “I am not a brain in a tank at Alpha Centuri”, that S knows q. This is because the fact that S’s belief that p co-varies with the truth of p, does not mean that, in cases in which S knows that p logical implies q, S’s belief that q also co-varies with the truth of q.  Hence, knowledge, which requires the co-variation of the fact that p and the belief that p, is not closed under known logical implication.

Upshot: The sceptic’s challenge that I do not know that I am awake and sitting in Jerusalem because I do not know that I am not a brain in a tank, which presupposes that knowledge is closed under known logical implication, misses its mark. 

CONCLUSION:

Nozick concludes that a belief counts as knowledge only if it tracks the truth.

DISCUSSION QUESTION:

1. Is Nozick’s truth-tracking account simply a version of the causal theory of knowledge? Why or why not?

2. What does it mean to say that knowledge is closed under known logical entailment?  Why does Nozick think that this view of knowledge is mistaken? Do you agree with Nozick? Why or why not?

3. Does Nozick hold that the sceptic is mistaken when she insists that we do not know that we are not brains in a tank at Alpha Centauri?  Why or why not? Do you agree? Why or why not?

4. Does Nozick hold that the sceptic is mistaken when she insists that, given that I do not know that I am not a brain in a tank, I do not know that I am currently sitting and reading a book? Why or why not? Do you think Nozick’s argument succeeds? Why or why not?