||The question of cognitive significance is a topic that is mainly associated with the logical positivism of the Vienna Circle in the early 20th century. The early logical positivists endorsed a principle of verification according to which the meaning of a proposition consists in the conditions under which the proposition may be verified (shown to be true). If no verifiability conditions exist for a proposition, then the proposition was taken to be meaningless. The principle of verification was taken to state conditions for the cognitive significance of claims about the world. Unverifiable or meaningless claims fail to have cognitive significance. The strict principle of verification was ultimately rejected by later positivists for various reasons, e.g. the apparent meaninglessness of the principle itself, as well as the implication of the meaninglessness of all non-observational propositions. Later positivists replaced the requirement of strict empirical verification with weaker requirements such as non-conclusive confirmation.