The principle of non-contradiction is necessary for the very possibility of thought, including the thought of the principle itself. Its denial is self-refuting since to deny the principle depends on the very principle itself. For if the principle of non-contradiction is not true, then the denial of its denial is just as valid as the denial itself.
Louis P. Pojman
Philosophical Traditions 2nd edition
Pg 194
1. What is the form of argument Pojman is using?
2. Contrast this with Hume on causation.
3. How does Pojman link the principle of non-contradiction and thought/belief?
4. What is a law of thought? How can we know there are laws of thought?
