Contrast rationalism and empiricism and evaluate responses to sceptical doubt

What this dot point is asking

You need to explain the rationalist and empiricist positions, set out the sceptical challenge, and assess the main replies.

Rationalism

Rationalism holds that reason, rather than sense experience, is the most secure source of knowledge, and that some ideas are innate. René Descartes sought a foundation immune to doubt. In his method of doubt he suspends belief in anything that could be mistaken, including the senses, mathematics and even the external world, imagining a deceiving demon. What survives is the cogito: even if deceived, I must exist in order to be deceived, so I think, therefore I am. From this certainty Descartes tries to rebuild knowledge.

The strength of rationalism is that it explains necessary truths, such as those of mathematics and logic, which seem to hold independently of any particular experience. Its weakness is the appeal to innate ideas, which empiricists find unverifiable, and the difficulty of getting from the certainty of the self to knowledge of the external world without circular reasoning.

Empiricism

Empiricism holds that all knowledge originates in experience. John Locke argued that the mind is a blank slate, or tabula rasa, on which experience writes, and that there are no innate ideas. David Hume pushed empiricism to its limits, distinguishing relations of ideas from matters of fact and arguing that beliefs about cause and effect rest on habit rather than reason. We never observe a necessary connection between events, only their constant conjunction.

Empiricism is admirably grounded in observation and fits the methods of science. Yet Hume's own rigour generates the problem of induction: we cannot justify inferring the future from the past without assuming the very uniformity of nature we are trying to prove. Strict empiricism also struggles to account for the certainty of mathematics.

Scepticism and replies

Scepticism denies that we have knowledge, or knowledge of some important kind. Descartes' demon and its modern cousin, the brain-in-a-vat scenario, suggest that our experiences could be exactly as they are even if the external world were illusory, so we cannot rule out being deceived.

Three responses are worth weighing. Descartes' own reply runs through the cogito to a non-deceiving God who guarantees clear and distinct perceptions, but this is widely judged circular, since the proof of God relies on the very faculties in question. The empiricist reply, especially in G. E. Moore, insists that our knowledge of ordinary things, such as that here is a hand, is more certain than any sceptical premise, so we should reject the premise rather than the conclusion. Immanuel Kant offered a more ambitious synthesis: knowledge requires both sensory content and the mind's own organising categories, such as causation, so the structure of experience is partly contributed by us and need not be read off a mind-independent world.

Evaluating

A strong answer treats rationalism and empiricism not as simple opposites but as emphasising different and partly complementary sources of knowledge, a tension Kant tried to resolve. On scepticism, the honest position is that radical doubt is hard to refute on its own terms, yet it is also self-undermining and practically idle, since the sceptic must still rely on reasoning to argue at all. The most defensible stance combines empirical grounding with rational structure and treats the demand for absolute certainty as itself questionable.