I think, therefore I am
Western philosophy in 17th and 18th centuries divided between British empiricism and continental rationalism. These theories are concerned with Epistemology… The theory of knowledge (how do we know what we know?)
Empiricists: only gain our knowledge from our senses. Born blank slate. No nonsense, no metaphysics. How can we prove things?
–Locke (key figure): No innate ideas – knowledge gained through experience
–Bacon: The scientific method – avoid the idols of the mind.
Rationalists: think we can learn about world just by thinking about it. No senses required, mind is important.
–Descartes, Leibniz, Spinoza – pure reason, the mind alone, or at least the pre-eminence of the mind.
Metaphysics.. trying to work out what reality is. What is beyond us?
Materialist – only material exists.
Idealism– deny existence of matter, and everything is ideas.
What I am aware of when I look at a chair is not the chair but how the table looks to me – it is the effect it produces in my mind when I look at it – this is the same for touching, tasting etc. -Berkeley. How can you prove that they actually really exist outside the experience my mind?
Rene Descartes
First half of 17th Century.. contemporary of Galileo and Shakespeare – seen as father of modern philosophy.
Held views in common with Galileo, Bacon etc – i.e.. opposed Aristotelianism and the traditional education available in the universities:
“I had gained nothing but an increasing recognition of my ignorance”
Descartes thought that by going back to a point at which no doubt was even possible and then rebuilding human knowledge by unmistakable steps – using knowledge that had been tested and was unquestionable. Wanted to strip out everything and go back to basics. His aim is incredibly ambitious – he wants to establish what it is possible to know – epistemology, theory of knowledge.
Wanted to try stripping back everything he knew and start again. Used analogy of barrel of apples.. empty all out start again one by one to check for the rotten one.
The project: the ‘method of doubt’ (Cartesian doubt) – radical doubt, thinking everything is wrong.
Dismisses any knowledge on which there are any grounds for doubt -it doesn’t matter if these grounds make you feel doubtful. How do we know our name is our name? How do we know our parents really are our parents?
Are there any beliefs that could survive this level of scrutiny?
Since your senses have sometimes deceived you (drunk, tired etc) once let down once, should dismiss idea as you cannot trust them – consider the possibility that they may deceive you at any time or that they may deceive you all the time, that they have no more status than a dream or hallucination.
The Evil Demon – what if it is all a dream? (The Matrix)
He is pushing skeptical arguments to their limit – is there anything that we can know for certain?
George Berkeley – there are just ideas.
But what about your belief that you are now thinking – but this is where the doubt is defeated, because doubting that you are thinking is still thinking – and if I am thinking then I must exist – hence Cogito Ergo Sum. Cogito is turning point.
If I have a thought, this means that I exist. Even if my thoughts are wrong, even if controlled by an evil demon, it still means that I exist. THIS is the certain knowledge he was searching for.
Descartes identifies ideas with mind. Body and mind separate. I relates to thinking self. If lose hand, still exist, thinking. Existence depends on mind not body. He is able to raise doubts about everything except his mind.
The mind is one thing – the body another. This is Cartesian dualism.
Mind = real person/self – body something else. are different but can interact.
Descartes epistemology sets off a tendency in European (German) philosophy called idealism – Kant, Hegel, etc.
After demolition of all his beliefs – except one – he has a problem. He is stuck in the Cogito – how is he to escape? How can establish world outside exists? Descartes needed it to prevent the Cogito simply collapsing into solipsism, which is intuitively absurd. The answer is… God. He needs to establish two things – that God exists and that God wouldn’t deceive us.
Trademark Argument
Descartes has the idea of God – it can’t have come from nowhere. God must have gave us the idea of him – as if he left a trademark, a logo, on us when he created us. God is a benevolent being and therefore wouldn’t deceive us.
The Ontological Argument (pg 535 HWP)
A priori (through idea of pure reason) argument for God’s existence. God is a perfect being so he therefore exists – he wold not be a perfect being if he didn’t exist. Once it has been established (to Descartes satisfaction) that God exists and that he wouldn’t deceive us, Descartes then starts to reconstruct his beliefs.
Other argument is
Cosmological argument or the existence of a first cause or uncaused cause. (everything has a cause.. first cause was God.)
Spinoza
Spinoza argues that if the world is separate from God then he has boundaries, so for God to be infinite he has to be part of the world. Therefore theres only one substance – not two like Descartes said- and this was God. This is monism – opposed to dualism. Russell later followed this view – calling himself a “neutral monist”.
It means that all our thinking is embodied – has a physical manifestation. Same substances just different applications.
This raises the question of cause and effect – if there is only one substance, how does causality work? The mind makes the physical stuff happen.
God or nature is the true substance. Berkeley – his view was similar – there was only one substance but it is mental.
Spinoza doesn’t believe in free will – human beings are not a separate reality…
they are simply aspects of God. Opposed by existentialists – spontaneity.
It is a type of Pantheism – something which would become very popular in the 18th and 19th centuries, Romanticism – a non-personified god or nature spirit which is eternal and unifying. Geist.
God did not create nature, God is nature and people are part/ aspects of God. This means that everything that happens is simply a manifestation of God – this eliminates sin and evil. Wise people must look at the universe from the point of view of God – past, present and future events unchanging.
Leibniz
A key idea for Leibniz is the idea of the Monad. The notion of substance – which is opposed to Spinoza.
A Monad is Leibniz word for substance. “Whatever is complex is made up of whats simple.” These are simple, non-divisible soul-like entities which lack extension or any physical characteristics.
Leibniz is saying that everything that is complex must be able to break down into simpler elements – until you get to the 100% genuine simple non-analyzable elements of matter etc. These things can’t be material. As the definition of material is something that can be extended – and extension is always divisible, so the ultimate constituents of reality must be immaterial and not occupying space.
Leibniz (Dr Pangloss) was mocked in book by voltaire who responds to endless disasters by declaring: “All is for the best in the best of all possible worlds.”
Candide responding “If this is the best, what must others be like?”
Other views:
Epiphenomenalism – Everything is simply physical.. physical beings, closed causality, physical brain – our inner lives are just the hum of the machine, it doesn’t move the machine its just a by product.
Huxley (1874), who held the view, compared mental events to a steam whistle that contributes nothing to the work of a locomotive.
Delay in brain reaction to physical impulse.. Body reacts faster, brain reacts to body.
Loosely defined 
very good notes
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