© Michael Lacewing Reason and experience Michael Lacewing

Epistemology How do we know what we know? Types of knowledge –Acquaintance: I know Oxford well. –Know how: I know how to ride a bike. –Propositional: I know that elephants are grey. Belief v. knowledge –Knowledge has a justification or evidence

A clear distinction Rationalism: we can have substantive a priori knowledge of how things stand outside the mind. Empiricism: we cannot.

Substantive knowledge Substantive knowledge is knowledge of a synthetic proposition. Trivial knowledge is knowledge of an analytic proposition. –An analytic proposition is true or false in virtue of the meanings of the words. –Not all analytic propositions are obvious: ‘In five days time, it will have been a week since the day which was tomorrow three days ago’ - true or false?

A priori knowledge A priori: knowledge that does not require (sense) experience to be known to be true (v. a posteriori) It is not a claim that no experience was necessary to arrive at the claim, but that none is needed to prove it.

Rationalism How can there be a priori knowledge? Innate ideas: we have ideas or knowledge ‘innately’ –We have an innate conceptual scheme A priori reasoning and intuition: we have a form of rational ‘insight’

Innate ideas Locke’s attack –All ideas (concepts and propositional knowledge) are available to consciousness –There is no idea or claim that everyone has from birth –Children must first learn or be taught concepts All concepts must be gained from experience

Innate ideas No major philosopher has defended innate ideas in Locke’s sense Innate ideas are ideas whose content cannot be gained through experience. We do not have the idea/concept from birth - experience must trigger our awareness of the idea, but the idea is not derived from experience. Triggering capacities: bird song, language

Innate ideas Core argument: experience is insufficient for forming the concept E.g. ‘physical object’: how can experience lead us to form the concept of something that exists independently of experience?

Origins of innate ideas Carruthers: innate ideas are genetically encoded, so that under certain conditions, we will develop the idea Descartes: innate ideas are part of our rational nature, dispositions to form certain thoughts through reasoning Plato: innate ideas are ‘remembered’ from a previous existence

A priori reasoning about what exists Can sense experience tell us about everything that exists? Moral values? God? Can sense experience, on its own, give us knowledge? What justifies the beliefs we form on the basis of sense experience? Descartes: How do I know that reality is the way I experience it? –The problem of the evil demon

The physical world What causes our experiences of the physical world? –Physical objects –Me –Evil demon –God Not me: I would know if I imagined them Not evil demon or God –These options would entail that God is a deceiver –God exists and is not a deceiver (ontological argument) Therefore, physical objects exist.

On human reasoning Can a priori reasoning establish anything except analytic truths? –Hume: ‘Nothing is demonstrable, unless the contrary is a contradiction.’ What can we know about the world that does not depend on sense experience?

Conceptual schemes Is sense experience where it all starts? Or does something have to exist before sense experience to make it ‘intelligible’? –Is it a jumble before we apply concepts? Origins of concepts: language (other people) v. structure of the mind (‘reason’) –Language: different languages have different concepts, so lead to different ways of understanding sense experience –Structure of the mind: this is common to everyone, so there is only one (basic) way of making sense of experience