“The logical positivists wished to eschew metaphysics, to escape transcendence, to leave behind forever the tyranny of an immaterial world of ideas. And so they devised a rigid criterion of knowledge: you cannot know anything you cannot empirically verify.  Suddenly, time-honored and venerable disciplines, such as history, ethics, and theology, found themselves unwelcome guests at the table of scientific discourse. Even mathematics itself felt its foundations shaken. But with little delay, logic came to its own rescue! The logical positivists' criterion did not meet its own demand: logical positivism is self-refuting. In short order, it became an amusing relic in the annals of undergraduate philosophy.”
 ~ Science Is as Science Does by Benjamin C. Richards