Questions: Skeptical Scenarios and Knowledge Closure

Question 1

You believe you have hands (H). A skeptic argues: H entails not-BIV; you cannot rule out BIV; therefore by modus tollens you do not know H. Fred Dretske's tracking account responds by:

• A. Accepting the conclusion — we do not know ordinary propositions in the strict sense
• B. Denying closure — your belief in H can track the truth of H without your belief in not-BIV needing to track its truth
• C. Arguing empirically that brain-in-vat technology is impossible
• D. Claiming the argument commits the fallacy of affirming the consequent

Answer: (B)

Dretske and Nozick deny that knowledge transmits through known entailment in the way closure claims. On the tracking account, you know H because there is no nearby possible world where you falsely believe you have hands. But BIV worlds are not 'nearby' — they are remote, bizarre scenarios. You need not track the truth of not-BIV to know H. This rejects closure as the premise that links ordinary knowledge to skeptical scenarios, rather than accepting skepticism or resorting to empirical arguments about technology.

Question 2

A contextualist response to the skeptical argument claims that the word 'know' in 'I know I have hands' means something different in everyday conversation than in a philosophy seminar where BIV scenarios are explicitly raised. This response:

• A. Denies the first premise — you actually can rule out BIV scenarios by observation
• B. Accepts skepticism but limits its scope to philosophical contexts
• C. Preserves ordinary knowledge claims by making knowledge-attribution context-sensitive rather than absolute
• D. Implies that knowledge is entirely subjective and culturally determined

Answer: (C)

The contextualist does not deny skepticism outright, nor does the response make knowledge purely subjective. It claims the standards for 'knowing' shift with context: in ordinary conversation, the BIV scenario is not a relevant alternative, so 'I know I have hands' is true. In a seminar where the BIV scenario is explicitly raised, standards are elevated, and the same claim may be false. Knowledge attributions are context-sensitive in the same way that 'flat' or 'empty' are — the semantics shifts, not the world.

Question 3

On the tracking account of knowledge, a person can know they have hands without knowing they are not a brain in a vat, because BIV worlds are not 'nearby' possible worlds where the person would falsely believe they have hands.

• T. True
• F. False

Answer: True

The tracking account requires that in nearby possible worlds, you would not falsely believe P. For H (I have hands), there is no nearby world where you lack hands but still believe you have them — nearby worlds are just slight variations on actual reality. BIV worlds are highly remote. So H is tracked. For not-BIV, the BIV world is, by hypothesis, indistinguishable from actuality — it is in some sense 'as close as it gets' experientially. So not-BIV is not tracked. This is precisely what allows the tracking theorist to preserve ordinary knowledge while denying closure.

Question 4

If epistemic closure is valid and you can seldom know you are not a brain in a vat, then you can seldom know any ordinary propositions — accepting closure forces acceptance of skepticism.

• T. True
• F. False

Answer: False

Closure combined with the inability to know not-BIV does yield the skeptical conclusion by modus tollens. But contextualism accepts closure while still preserving ordinary knowledge — by arguing that in ordinary contexts, you DO know not-BIV (because the BIV scenario is not a relevant alternative in that context). So closure is compatible with rejecting skepticism if knowledge is context-sensitive. Accepting closure does not force skepticism; it forces a choice between skepticism, denying closure, or contextualizing knowledge.

Question 5

Why does the skeptical argument run the closure principle via modus tollens, and what does this reveal about the relationship between ordinary knowledge and knowledge of skeptical scenarios?

Model answer: The argument runs: (1) You cannot know not-BIV. (2) If you knew H, closure would require you to know not-BIV (since H entails not-BIV). Therefore (3) you do not know H. This is modus tollens on closure: instead of transmitting knowledge forward from H to not-BIV, it transmits ignorance backward from not-BIV to H. This reveals that ordinary knowledge and knowledge of skeptical scenarios are not independent — closure links them. You cannot comfortably say 'I know I have hands' while also saying 'I have no idea whether I'm a brain in a vat,' because the first entails the second. Any theory of knowledge must explain why ordinary knowledge is secure despite the apparent impossibility of ruling out skeptical scenarios.

The modus tollens move is the argument's real bite. Closure was designed as a forward principle (knowledge transmits through deduction), but it cuts both ways. The skeptic uses it backward: inability to know the entailed conclusion infects knowledge of the premise. Solutions must either block the backward transmission (deny closure), accept it but limit its scope (contextualism), or accept the full skeptical conclusion.