(Read Part 8 of the series.)

A Return to Scepticism

The Scottish philosopher David Hume accepted Locke’s empiricism and also agreed with Berkeley that we cannot ever know that there is a world outside of and separate from ourselves. Indeed he claimed not to understand what people meant by the idea of ‘substance’. We only know about perceptions, colour, sound, taste and so on. If this thing called ‘substance’ is something else, we have no knowledge of it – why invent it? If we took away the sensible qualities of things there would be nothing left, would there? Why should we need anything to explain or support our perceptions and impressions? Questions about why they arise are unnecessary and the answers suggested to explain them are unintelligible. The idea of ‘mind’ is just as illogical. If we simply dropped both of them, we would have no need to try to imagine ways in which such supposedly different ‘things’ might interact, as Descartes had wasted so much of his time doing.

He was also sceptical of Descartes’ conviction of his own existence as a thinking individual and made his own attempts to find some irreducible ‘self’ of which he could be certain. He decided that, whenever he attempted to look for ‘himself’ he could only find thoughts, feelings and perceptions; never a ‘self’ that is the perceiver, feeler and thinker. And so he concluded that there was no such thing. One feels one wants to get hold of him and shake him and say: “Yes, when you look, all that you find are thoughts, feelings and perceptions but who is it who finds this? What is the ‘who’ that is doing the looking?” He also felt similarly about God. We may well feel convinced that there is a God – this is effectively the definition of faith, a firm conviction without any empirical evidence – but this is not the same as knowledge.

There are really only two useful types of thought according to Hume. Reasoning based upon mathematical concepts is based upon ideas that can be known intuitively to be true and they do not rely upon any external beliefs. Direct impressions that arise from observation and can be tested through experience are the other type. Anything else is ultimately irrelevant because it can never be validated. He famously said that any books dealing with other things (amongst which we must include the Bible, for example) should be ‘committed to the flames’, “for it can contain nothing but sophistry and illusion”. The quotation about the metaphysician’s black cat given earlier could have been made by Hume.

In fact he was scathing about the pursuits of metaphysicians who deceived themselves with their inventions of clever explanations for things that could never be explained, thinking that the terms that they had devised were actually significant and intelligible. He thought that poets and children could be excused such flights of imagination but not supposedly intelligent philosophers. Hume would claim that the sorts of questions being posed on this website are not really meaningful. We cannot directly experience, define, investigate or test the things about which we are asking questions. How can we hope to find valid answers and how would we know if we did? Still, if we find it amusing…

Hume also had strong, counter-intuitive views upon the subject of causality. We take it for granted in our day-to-day life that some things cause other things. Indeed this is so fundamental that we rarely give it any thought. We put water in the kettle for our cup of coffee in the morning and flick a switch. Unless there has been a power cut, we simply know that, in a couple of minutes the water will come to the boil. Electricity flowing through the heating element causes the water to heat up. But Hume pointed out that we do not ever see something called ‘causality’. All that we are aware of is that, in all of the situations that we have encountered previously, one thing has been followed by another. We have not experienced a situation in which, for example, the kettle did not come to the boil after switching on – unless the fuse in the plug had blown or the lead had come loose etc., i.e. unless there was some other condition to explain why, thus constituting a different ‘cause’ for the failure.

All that we can say is that B has always followed A in our experience. But our experience has been minimal in terms of the infinite universe and it is a gross assumption to think that B will continue to follow A for the rest of eternity. Also, our understanding is limited. We might, for example, once have claimed that day ‘causes’ night. After all, night has always followed day in our experience. But we now know that these are both inevitable consequences of the earth’s rotation as it moves around the sun so that the notion of cause and effect between the two does not apply.

In the case of the kettle above, we might also believe that we know that, if we switch it on and raise the temperature of the water to 100⁰ C, then the water will boil. However, if this is done at the top of a mountain, where the air pressure is much lower, it will (usually!) be found that it will boil quite a few degrees lower than this. Conversely, if heated in a pressure cooker, for example, the water will not boil at all at 100⁰ C. In fact, it has only been observed to boil at precisely this temperature under normal atmospheric pressure. But Hume maintained that there can be no evidence that any of this will happen next time. We might find that it boils as soon as we switch it on, even though the water has just come out of the cold tap or we might find that it will not boil at all. Either of these eventualities would pose some interesting problems for Physics but that is not the point.

When it comes to our own desires and actions, we assume that if we want Y, then we have to do X. Of course many things can go wrong in human affairs, which tend to be more complex than boiling water, but nevertheless we rely on causality. Without it, motivation and purposeful action would be meaningless. In fact, we rely on habit. What has happened before in our interactions with things will happen again. We discover that fire burns when we are children and periodically reinforce this throughout our lives. The two things have been experienced as going together and the related ideas are connected in our minds. But, if we think that we want to get up when the alarm clock rings in the morning and then later find that we are washing ourselves in the bathroom, we may say that we ‘decided’ to get up and that this was the cause of our getting up. In fact, a myriad things have occurred in this process, involving electrochemical reactions in the brain, hormones in the blood, oxygen absorption in the lungs and thousands more, most of which we would not claim to be able to control. It also involves the thorny question of free will, which will be addressed in much more detail later (if you can’t wait, you will already find an article of mine written on this topic for Yoga International magazine at http://advaita-academy.org/Articles/The-Paradox-of-Free-Will.ashx).

We cannot help but believe in things, external and internal, and in causes and effects between them but we do so only through habit and because it is easy and convenient to do so. Rationally, we have no justification for any of these beliefs. This is the extreme position of scepticism at which Hume arrived. There is equally no point in studying philosophy except in so far as it is an interesting way of passing the time. All our actions are ultimately irrational since they can never be based upon any real knowledge. The reaction to these claims from contemporary philosophers was not to refute them but to resort to faith and emotion, effectively arguing that the heart outranked the mind on such matters. His demonstration of the unreasonableness of the empirical method led to the growth of ‘unreason’ as a reaction.

Go to Part 10