He published works on Leibnitz, empiricism and scepticism in Hume's philosophy, modern pessimism, Kantic criticism, English philosophy, Heraclitus of Ephesus and many other subjects.
They are also the direct antitheses to the scepticism of Montaigne and Pascal, to the materialism of Gassendi and Hobbes, and to the superstitious anthropomorphism which defaced the reawakening sciences of nature.
The application of "common sense" to the problem of substance supplied a more satisfactory analytic for him than the scepticism of Hume which reached him through a study of Kant.
But he does not follow his idea into the details of human duty, though he passes in review fatalism, mysticism, pantheism, scepticism, egotism, sentimentalism and rationalism.
The Scottish philosophy of Thomas Reid and his successors believed that David Hume's scepticism was no more than the genuine outcome of Locke's sensationalist appeal to experience when ripened or forced on by the immaterialism of Bishop Berkeley - God and the soul alone; not God, world and soul.