Knowledge must be grounded in evidence in accordance with epistemological principles. This monograph distinguishes two kinds of principle: rules of evidence and rules of justification.
Rules of evidence, such the canons of inductive and deductive logic, specify what sort of evidence is relevant to what sort of conclusion. Rules of justification specify what a person's cognitive state must be if he is to be justified in accepting a conclusion. This distinction makes it possible to explain how our knowledge can be fully justified all the way down to its foundations in perception.
About David Kelley: David Kelley is a professional philosopher, teacher, and best-selling author. After earning a Ph.D. in philosophy from Princeton University in 1975, he joined the philosophy department of Vassar College, where he remained until 1984. He taught cognitive science at Brandeis University as a Visiting Lecturer. Among his books are Unrugged Individualism: The Selfish Basis of Benevolence; The Contested Legacy of Ayn Rand; and The Art of Reasoning, one of the most widely used logic textbooks in the country. With Roger Donway, he co-authored Laissez Parler: Freedom in the Electronic Media, a critique of government regulation. He is also the author of A Life of One's Own: Individual Rights and the Welfare State, a critique of the moral premises of the welfare state and defense of private alternatives that preserve individual autonomy, responsibility, and dignity.
His articles on social issues and public policy have appeared in Harper's, The Sciences, Reason, Harvard Business Review, The Freeman, and elsewhere. He has been an editorial writer for Barron's, has appeared on 20/20 and the ABC News special, "Greed" With John Stossel, and has written and lectured extensively on issues in philosophy, politics, and public affairs.
An active proponent of Objectivism for more than 25 years, he has lectured to student groups at Harvard, Yale, University of Michigan, Berkeley, Amherst, and many other colleges and universities. He has also addressed the Mont Pelerin Society, the Free Press Association, the Cato Institute, and Heartland Institute, as well as many Objectivist conferences.