Certainty

Certainty is a point on the continuum of knowledge: a conclusion is certain when the total of the available evidence points in one direction and there is nothing left to suggest another interpretation. Objectivism holds that certainty so understood is achievable by a finite mind, because it is measured against the evidence a person actually has rather than against omniscience.

“A conclusion is "certain" when the evidence in its favor is conclusive... the total of the available evidence points in a single direction... there is nothing to suggest even the possibility of another interpretation. There are, therefore, no longer any grounds for doubt.”
   ~ Leonard Peikoff, Objectivism: The Philosophy of Ayn Rand, chapter 5

The continuum

Objectivism does not treat a claim as simply known or unknown. Between an idea first entertained and one fully established there are stages, and the distinction among them is the amount of evidence, not the strength of anyone's conviction:

• Possible — there is some evidence for the claim, not enough to conclude anything, and no evidence against it.
• Probable — the evidence substantially supports it, but something in the known context still points elsewhere.
• Certain — the evidence is conclusive. Nothing in the available context supports any other interpretation.

Below the bottom of this scale sits a fourth category that is not on it at all. A claim advanced with no evidence is arbitrary: it is neither true nor false, neither possible nor improbable, because nothing has been offered to evaluate. Objectivism holds that the arbitrary is to be dismissed rather than argued with, and this is what does most of the work in the sections below.

Certainty is contextual

The traditional objection to certainty runs: you cannot rule out that something you have not yet discovered will overturn your conclusion, therefore you are never entitled to be certain.

The Objectivist answer is that this sets the standard at omniscience and then observes that men are not omniscient. Since no finite mind could ever meet it, the demand is not a high standard of rigour; it is a rejection of the possibility of knowledge disguised as one. See Skepticism.

The standard Objectivism uses instead is the full context of the evidence available. A conclusion validated against everything one knows or could reasonably obtain is certain, and remains so. What later discovery can do is extend it or mark its boundaries:

• Newtonian mechanics was certain within the range of phenomena the seventeenth century could observe, and it is still correct within that range. Relativity did not show it false; it showed where it stops applying.
• A doctor certain of a diagnosis on conclusive evidence is not proved wrong by a disease discovered a century later. He was right about what he had.

The requirement is not weak. It is the full context: a conclusion reached by ignoring available evidence, or by not looking where one had reason to look, is not certain but evaded. See Volition and Objectivity.

What certainty is not measured by

Certainty is an epistemological status, not a feeling. A person can feel sure of an unfounded belief and can feel uneasy about a proved one; neither state affects what the evidence supports. See Emotions.

This also settles what counts as grounds for doubt. A doubt must be based on evidence. "It is conceivable that things are otherwise" is not a ground, because bare conceivability is arbitrary — it cites nothing. If it were admitted, every conclusion could be unsettled by anyone with an imagination, which is exactly the manoeuvre the arbitrary category exists to block.

Common misunderstandings

• That contextual certainty is certainty with an escape hatch. The context is stated, not smuggled. A contextually certain conclusion has a known scope, and finding its edge is not the same as finding it false. See Truth.
• That it means never revising anything. Conclusions are revised when evidence warrants it. What is denied is that the mere possibility of unknown evidence warrants it in advance.
• That certainty requires infallibility. It requires having met the standard of proof in one's context. Men are fallible, which is why the method matters and why error is possible — but a fallible faculty used correctly still reaches knowledge. If it could not, the claim that men are fallible would be unknowable too.
• That "I might be wrong" is a virtue of intellectual humility. Held as a general policy rather than a response to specific evidence, it is the stolen concept again: it asserts as certain that certainty is unavailable.

See also

• Context · Truth · Knowledge · Proof · Arbitrary
• Induction · Logic · Reason · Objectivity
• Skepticism · Faith · Emotions · Axioms
• Fallacy of the stolen concept · Fact

Discussion

• "The only thing I know is that I don't know anything"
• How does Objectivism disprove skepticism?
• A criticism of Objectivist epistemology

References

• Peikoff, Leonard. Objectivism: The Philosophy of Ayn Rand, chapter 5 — the continuum of knowledge and the status of the arbitrary.
• Rand, Ayn. Introduction to Objectivist Epistemology. The Objectivist, 1967.
• Harriman, David. The Logical Leap: Induction in Physics. New American Library, 2010.

External links

• Certainty at the Ayn Rand Lexicon