Descartes' rationalism/ thesis essay plan

Descartes’ intuition and deduction thesis

gain new knowledge through reason alone

about methods

rationalism: undeniable, foundational truths

deduction to produce further truths

reason + a priori > indubitable

intuition: certain truths = necessity

ability to reason, recognise self-evident truth

deduction: work out other truths based on this

foundationalism: foundational truth, reason

Descartes on gaining knowledge

Intuitions such as that we exist and then use them as the premises in deductive arguments to ultimately prove God’s existence and the existence of the external world

We can gain synthetic knowledge through a priori means (intuition and deduction)

intuition

the rational mind apprehends the truth or falsity of something with immediacy, without any process of reasoning or interference

deduction

using premises to reach a conclusion, whose truth is entailed by the truth of the premesis

Descartes’ cogito and clear and distinct

the cogito is a clear and distinct idea, and known to be true

so clarity and distinctness is a sign of truth

cannot doubt own existence

empiricist criticism of cogito

Hume: only derive knowledge from experience

when thinking about own mind, we only ever experience particular mental states

ourselves = a bundle of ever-changing mental states

descartes’ defense of cogito

it is clear and distinct that thoughts require a thinker

REPLY: just a common-sense understanding, if doubting everything the doubt that too

Descartes’ trademark argument for God

we have an idea of God as a perfect being

the idea of perfection cannot originate from an imperfect being (us)

only a perfect being could have placed this idea in us, like a trademark

so, god exists

(there must be as much reality in the cause as there is in the effect)

empiricist response to trademark

concept of God created by our minds

copy principle: all ideas stem from sense impressions

imagine finite human qualities, negate imperfection

Descartes’ defense of trademark

recognising imperfection presupposes that you have the idea of perfection

but Hume claims that we deduce perfection from imperfection?

Hume’s fork as a criticism of the thesis

relations of ideas and matters of fact

a priori reasoning, relations, analytic truth

a posteriori, matters, synthetic

intuition and deduction uses a priori to come to a conclusion about matters of fact! conclusion not justified by only analytic knowledge about relations, not synthetic so tells us nothing real about the world