LEIBNIZ ON KNOWLEDGE OF NECESSARY TRUTHS -- Locke's arguments against innate knowledge -- LEIBNIZ'S RESPONSE TO LOCKE -- Thinking harder: experience triggers innate knowledge -- ALTERNATIVE EMPIRICIST ACCOUNTS -- Locke's argument against innate concepts -- REJECTING LOCKE'S DEFINITION OF 'INNATE CONCEPT' -- LEIBNIZ'S DEFENCE OF INNATE CONCEPTS -- The mind as a 'tabula rasa' -- LOCKE'S TWO SOURCES OF CONCEPTS -- HUME ON IMPRESSIONS AND IDEAS -- SIMPLE AND COMPLEX CONCEPTS -- Issues with the empiricist theory of concepts -- Thinking harder: challenging the copy principle -- LEIBNIZ ON 'INTELLECTUAL IDEAS' -- Thinking harder: the concept of substance -- Key points: innatism -- B. The intuition and deduction thesis -- Rationalism and empiricism revisited -- THE MEANING OF 'INTUITION' AND 'DEDUCTION' -- EMPIRICIST ALTERNATIVES -- Hume's fork -- Descartes' theory of rational intuition -- The cogito -- Clear and distinct ideas -- EMPIRICIST RESPONSES TO THE COGITO -- CLEAR AND DISTINCT IDEAS AND GOD -- Descartes' Trademark argument -- Thinking harder: degrees of reality -- EMPIRICIST RESPONSES TO THE TRADEMARK ARGUMENT -- Descartes' cosmological argument -- EMPIRICIST RESPONSES TO DESCARTES' COSMOLOGICAL ARGUMENT -- Descartes' ontological argument -- EMPIRICIST RESPONSES TO DESCARTES' ONTOLOGICAL ARGUMENT -- Descartes' proof of the external world -- The concept of a physical object -- Thinking harder: the existence of physical objects -- EMPIRICIST RESPONSES TO DESCARTES' PROOF OF THE EXTERNAL WORLD -- Key points: the intuition and deduction thesis -- Summary: reason as a source of knowledge -- IV. The limits of knowledge -- A. Philosophical scepticism -- The particular nature of philosophical scepticism -- AM I A BRAIN IN A VAT? -- THE DISTINCTION BETWEEN PHILOSOPHICAL SCEPTICISM AND NORMAL INCREDULITY -- THE ROLE/FUNCTION OF SCEPTICISM WITHIN EPISTEMOLOGY