Someone is absolutely convinced — beyond any doubt — that a medical remedy will cure them, despite having no good evidence. According to infallibilism, do they know this?
AYes — infallibilism requires certainty, and they feel certain, so they know
BNo — psychological certainty (feeling sure) is not what infallibilism requires; it requires that error be epistemically impossible
CYes — as long as the belief turns out to be true, infallibilism counts it as knowledge
DNo — infallibilism requires empirical evidence, which they lack
Infallibilism requires that one's epistemic position make error logically impossible — a guarantee, not a feeling. Psychological certainty (feeling absolutely sure) is entirely separate: people feel certain about false beliefs all the time. The infallibilist condition is not 'I cannot imagine being wrong' but 'my epistemic situation logically excludes the possibility of error.' Since this person has no sound epistemic basis, error is clearly possible — infallibilism denies knowledge regardless of subjective confidence.
Question 2 Multiple Choice
Which domain provides the strongest case for infallibilism, and why?
APerception — because we have immediate, direct access to our sensory experiences
BMemory — because past events are fixed and cannot change
CMathematics and logic — because a correct proof guarantees the conclusion given the axioms and rules
DTestimony — because reliable sources eliminate the chance of error
Mathematical proof provides the clearest example of infallible epistemic access: if you have correctly proven a theorem from accepted axioms using valid logical rules, you cannot be mistaken about the conclusion given those axioms. The proof guarantees the result. Perception is subject to illusions and hallucinations; memory is fallible and reconstructive; testimony depends on source reliability, which is always logically possible to be wrong about.
Question 3 True / False
Infallibilism implies that we cannot have knowledge of most empirical facts, since for nearly any empirical belief it is at least logically possible to be mistaken.
TTrue
FFalse
Answer: True
This is one of infallibilism's most significant implications and its main cost. For empirical claims — 'there is a cup on the table,' 'it rained yesterday' — the possibility of perceptual illusion, memory error, or systematic deception is always logically open. Infallibilism requires that these possibilities be closed for knowledge to obtain, which they almost never are. Infallibilists typically respond by restricting knowledge to non-empirical domains or by accepting that we know far less than we ordinarily claim.
Question 4 True / False
Infallibilism and radical skepticism are the same view, since both imply that humans know very few things about the empirical world.
TTrue
FFalse
Answer: False
They share a conclusion about empirical knowledge but differ fundamentally in structure. Infallibilism is a positive theory about what knowledge requires — namely, infallibility — and can consistently hold that we do know mathematical truths and logical tautologies, where infallibility is achievable. Skepticism is a thesis that knowledge is absent, typically across all domains. An infallibilist can be a non-skeptic about a priori knowledge; a radical skeptic denies knowledge everywhere.
Question 5 Short Answer
Why doesn't infallibilism collapse into skepticism, even though it implies we know very little about the empirical world?
Think about your answer, then reveal below.
Model answer: Infallibilism restricts the scope of knowledge to domains where genuine epistemic guarantee is achievable — primarily mathematics, logic, and perhaps introspection — rather than denying that knowledge exists at all. Within these domains, infallible knowledge is possible: a correct proof cannot be wrong. Skepticism goes further, denying knowledge even in these privileged domains. Infallibilism also makes a conceptual claim (knowledge requires infallibility) rather than the empirical claim that infallible access is never achieved.
The key move for the infallibilist is to reserve the word 'knowledge' for genuinely guaranteed beliefs while acknowledging a rich class of justified, well-evidenced beliefs that we ordinarily call knowledge but that technically fall short. This creates a terminological revision rather than practical nihilism about inquiry.