Verifiability (or verification) principle

Principle that to be meaningful a sentence or proposition must be either verifiable by means of the five senses or a tautology of logic.

The verifiability might be required in practice or (more usually) in principle, and might need to be conclusive (strong verifiability) or could be merely partial (weak verifiability).

Mathematical sentences are treated as tautologies. All others (of metaphysics, ethics, religion, and so on) have meaning, if at all, only in some secondary way (see also speech act theories).

Sometimes the principle says that the meaning is the method of verification, and then the principle can be called the verifiability (or verification) theory of meaning, though this title sometimes refers simply to the claim that the principle, however formulated, should be accepted.

Among objections to the principle are that it cannot apply to itself, and is in danger of excluding too much (propositions in science and history, and so on); but a derivative of it has recently appeared as anti-realism.

Also see: logical positivism

A J Ayer, Language, Truth and Logic (1936); 2nd edn with important new ‘Introduction’, 1946


  • Verification and validation, in engineering or quality management systems, is the act of reviewing, inspecting or testing, in order to establish and document that a product, service or system meets regulatory or technical standards
    • Verification (spaceflight), in the space systems engineering area, covers the processes of qualification and acceptance
  • Verification theory, philosophical theory relating the meaning of a statement to how it is verified
  • Third-party verification, use of an independent organization to verify the identity of a customer
  • Authentication, confirming the truth of an attribute claimed by an entity, such as an identity
  • Forecast verification, verifying prognostic output from a numerical model
  • Verifiability (science), a scientific principle
  • Verification (audit), an auditing process


  • Punched card verification, a data entry step performed after keypunching on a separate, keyboard-equipped machine, such as the IBM 056 Verifier
  • Verification and validation (software)


  • CAPTCHA, device to verify that a user of a website is human, to prevent automated abuse
  • File verification, checking the formal correctness or integrity of a file
  • Speech verification, checking of the correct speaking of given sentences
  • Verify (DOS command)

Software development

  • Formal verification, mathematical proof of the correctness of algorithms
  • Intelligent verification, automatically adapts the testbench to changes in RTL
  • Runtime verification, during execution
  • Software verification, an overview of techniques for verifying software

Circuit development

  • Hardware verification
  • Functional verification of design of digital hardware
  • Analog verification, applies to analog or mixed-signal hardware
  • Physical verification, design of a circuit

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