Shabbir asked:
Am I or am I not a skeptic of the external world?
For my philosophy class I must write a paper in which I have to choose
(1) Why I am a skeptic about the external world
or,
(2) Why I am not a skeptic about the external world.
I have to give my explanation based on the Philosophers Renee Descartes and David Hume.
I am having trouble understanding both sides of the argument. I have a superficial understanding that Descartes used rationalism while Hume used empiricism.
Can somebody please help me develop some ideas based on Descartes and Hume?
Answer by Craig Skinner
I see you may be a skeptic (USA), whereas I may be a sceptic (UK).
Clearly you’re not – you think there are other people with computers who can email you advice. And you are right – here I am. And you think real examiners will mark your essay. Nobody is a sceptic in ordinary life – we all believe the external world exists and act accordingly.
The question is can we justify that belief.
The answer, I think, is that the existence of the external world cannot be proved either by reason or by observation, but we all believe it true, and it probably is.
Berkeley famously denied that there was such a thing as matter, and said the external world was composed of ideas in God’s mind, which are also sometimes in our minds. But mostly people think the external world is composed of matter (whatever that is exactly) and I will take this to be what we mean by external world (a material world).
Yes, Descartes was a rationalist, Hume an empiricist. Descartes thought he could prove (by reason, a priori) the external world exists. Hume took a dim view of reason, thought it could prove far less than we sometimes think, certainly not the existence of an external world. And he felt that the latter couldn’t be empirically proven (by experience and observation) either.
Descartes was no sceptic about the external world. Indeed he made important contributions to physics, and his whole philosophy is intended to provide a method of ‘rightly conducting reason and reaching truth in the sciences’. In that philosophy, notably in his Meditations, he intends to sweep away the old mediaeval speculations and start from the beginning, accepting only what he can be absolutely sure about and reasoning from there to see where it gets us. This is his Method of Doubt. As a ploy, he pretends to be a sceptic, doubting the existence of an external world including his body (at any moment, he cant be sure he’s not dreaming), doubting even that 2+2 makes 4 (an evil demon could be manipulating his mind), for the purpose of his arguments. He is a Methodological Sceptic. Famously, he says that if he is doubting, then he must exist, and this is his foundation – ‘I think therefore I am’. Fair enough. But his argument after that is dodgy. He says he has a clear and distinct idea of God; that this idea includes necessary existence, so God exists; and God is no deceiver so if Descartes clearly and distinctly perceives something it will be correct; he has such perceptions of an external world, including his body, and other people; lo and behold the external world exists. To mention just one flaw: his argument is circular – he knows God exists only by clear and distinct perception. But he can only rely on clear and distinct perception because God (a non deceiver) guarantees it.
Anyway, although his arguments convince few people, his scepticism is famous. But note he is only a Methodological Sceptic. Not a Philosophical one – on the contrary he thought he could show the existence of the external world (and much else) by reason.
Hume was a Philosophical Sceptic. He felt reason tells us much less than we sometimes think. We often think it ‘stands to reason’ that there is an external world, that I have a ‘self’, that I see cause and effect in the world. But all of this says Hume is just habits of the mind. We don’t, for example, really see cause and effect. All we see is one thing following another time after time, and our mind comes to expect the second thing if we see the first. We don’t actually see any connection between the two. Similarly if we ‘look inward’ we never catch an unattended self, just sensations and feelings (a bundle of perceptions). As for the external world, he simply says that he attempts no explanation as to what causes our impressions and ideas. We just cant help believing in an external world, a self, cause and effect. That’s the kind of creatures we are. We all do, he says, in everyday life – when we leave our philosophical reflections behind in the study and enter the hurly burly of ordinary life, these sceptical arguments seem weak and strained ad have no grip on us. So Hume is a Philosophical Sceptic (about the external world and much else).
For completeness, note Pyrrhonian scepticism (after Pyrrho, ca 300 BCE), not scepticism as method, nor as a philosophical stance, but as a way of life – be agnostic about everything, committing yourself to nothing, arguing neither for nor against any position (all are uncertain), supporting no cause, party or movement etc. A view with few takers.
So, you can choose:
1. I’m no sceptic. There definitely is an external world – it’s made of ideas (Berkeley’s idealism)
2. I’m no sceptic. There definitely is an external world – it’s made of matter (everyday view)
3. I’m no sceptic. There definitely isn’t an external world – it’s all in my mind (Solipsism)
4. I’m a philosophical sceptic. We cant prove the external world exists (but in ordinary life I assume it does, and am pretty sure I’m correct)
5. I’m a methodological sceptic, it’s a good ploy in philosophical arguments. Of course, we cant prove the external world exists (unless we accept Descartes’ argument),
Ask a Philosopher 
