During the time of developing their own ideas and philosophical views, the positivists believed that everything that was meaningful had to be verifiable and logically solved. Nothing could be truly meaningful A posteriori. In following this assertion, the Positivists created what is known as the VCM or the verifiability criterion of meaning. This principle states that a statement is meaningful if and only if it can be proven true or false, at least in principle, by means of experience. This notion follows along with the analytic and synthetic distinctions of statements. Analytic statements are believed to be A priori, meaning that they are logical and do not need sensory experience to be qualified as meaningful. However, Synthetic statements are believed to be A posteriori; the notion that the statement has to be verified through experience to be meaningful. Some problems that arose with the VCM was that not only was itself not verifiable in meaning, but it was too strict in what it designated to be meaningful. A common example is the notion of quantum particles or gravitational fields. These are theories that are quite relied on and believed by many scientists and they are not able to be experienced through the senses. Does this mean they are meaningless? According to logical positivism, they would be. However, scientists today know that this is incorrect and ultimately led to the distrust in the VCM.