To: Kerryn C.
From: Geoffrey Klempner
Subject: The significance of philosophical scepticism
Date: 30th October 2008 12:13

Dear Kerryn,

Thank you for your email of 24 October, with your second essay for Possible World Machine, in response to the question, 'Assess the significance of philosophical scepticism.'

I like the way you start off by considering the possibility of scepticism with respect to the question whether you have, as you believe, succeeded in learning something about the topic of scepticism.

A famous knock-down argument against the sceptic is to challenge the sceptic to state whether or not he 'knows' that scepticism is true. Either way, he is sunk.

There is no problem with the idea of 'acquiring knowledge about scepticism', provided that the knowledge in question is knowledge of what sceptics say, the arguments they put forward, and, crucially, the considerations which may be brought to bear in order to defeat those arguments. The difficulty arises only if, in the process of learning about scepticism, you have become convinced that the sceptic's case is sound. What do can you say then? How can you claim that you 'know' that scepticism is true?

We need to distinguish different levels and extremes of scepticism. You focus first on Descartes' doubts about the senses. We can use our senses to check on the reliability of our senses. But such checking can only go so far. There is no way that Neo (in the film, 'The Matrix') can discover merely by using his senses that he is asleep in a pod, where he has spent his entire life. Using his senses, Neo can only discover facts about his surroundings, which he takes for something 'real'.

Neo may worry that 'something is wrong with the world'. Perhaps he even sees anomalies (things mysteriously appearing and disappearing). And perhaps, if these anomalies became sufficiently severe or noticeable, there might be scope for putting forward, as a hypothesis, that he being fed experiences down a tube -- as far-fetched as that might seem. However, one crucial respect in which Neo's world differs from the theory of an evil demon envisaged by Descartes is that *space exists*. I may be dreaming, but there are material things out there, somewhere. But how do I know this?

The idea of being 'sceptical about the existence of a material world' is a more extreme version of scepticism. However, it is possible to go even further -- further than Descartes was prepared to go.

At each stage of his argument, Descartes relies on reason. If reason can be relied upon, then there is no contradiction in saying that I have 'learned that scepticism is true'. My 'learning', my philosophical 'knowledge', consists purely in the arguments which I have mastered against the hypothesis of empirical knowledge. In other words, you can be sceptical about *everything else*, and feel confident in your knowledge that scepticism is true, provided that you hold on tight to reason.

But why stop there? Who is to say that reason is to be trusted? Just as our senses can sometimes deceive us, so we can be deceived by reason. We fall victim to fallacies. We forget things. We miscalculate. All the evidence is that reason is a powerful tool but it is not infallible. But now, once this point is conceded, then the standard sceptical argument comes into play. How do you know that your reason only deceives you sometimes and not always? What higher authority can you cite, to corroborate the claims of reason, once these claims have been questioned?

You give as an example the film The Lake House, in which two characters who never meet, communicate by leaving letters in a mailbox. It would be very strange indeed if I found letters in a mailbox which had not been written by *somebody*. It would be just as strange if each letter continuing the conversation was written by a different 'somebody' (unless, of course, the letter writers were working as a team). However, there is a potentially far more troubling scepticism in the idea that, as one of the participants in the dialogue, my picture built up of the letter writer is totally off the mark; that I am being played along with a string of lies.

In the real world, when we put aside philosophy text books and the arguments of historical philosophers, there is real scope for scepticism: not about the senses, nor about reason, but about 'the other'. Relying on written letters to communicate merely underlines the problem which ordinary people face every day. The people we encounter our colleagues, friends and family; how can we ever be sure that they are as they appear? One of the tragedies of the human condition is the ever-present possibility of doubt about another person, their commitment or their sincerity or their love. Philosophy cannot help. The possibility of human relationship ultimately rests on faith.

All the best,

Geoffrey