This week, In Our Time with Melvyn Bragg discusses Common Sense Philosophy. Is common sense innate as Plato and the Stoics argued, or must it be learned? The later Cambridge Platonists argued against the materialists that our knowledge of God and morality is innate and given by God.
In 1690 John Locke challenges this in the essay on human understanding arguing that diversity of beliefs and senses in the history of thought opposes it and makes us lazy. In the 17th and 18th Century, Descartes wanted to found science on a reliable foundation and argued the proposition based on human existence which cannot be doubted: cogito ergo sum. Locke argued that there are properties of things which give us direct access to things outside our heads. Hume says there is no way of proving the validity of inductive reasoning. Can rationalist philosophy provide proofs? Our human nature provides evidence of the existence of the external world but not proofs.
Thomas Reed in Aberdeen, a minister of the Kirk, and his circle receive Hume's ideas well although the Aberdonians were not skeptics. He argues there are common sense principles: we exist and have a mind, and we can trust our senses generally along with the testimony of others e.g. on evidence for miracles and faith in general. There should be a unity between life in the real world and your philosophy. We have direct access to the real world.
Subsequently Immanuel Kant argues in the Critique of Pure Reason that events represented in the mind are orderly and it is through them that we know the world indirectly.