The French philosopher René Descartes adopted scepticism as his position from which to view the world. He explained this with an image. Imagine, he says, that there is a demon that continually seeks to deceive you about the world. Then you can take nothing for granted. What you think is true may be false; what seems to be the physical world with its laws may simply be a delusion. How then can we know anything?
We obviously need to find something that we can be sure of and then build on this as a secure foundation. But if all is deception and delusion, what can we ever be sure of? Descartes thought he had found it in what has become known as “the Cogito“, the Latin phrase “cogito ergo sum” or “I think therefore I am”. Another way of putting this is that if we are deceived, then there must at least be someone or something that is deceived: thus at least one thing exists and fortunately it is a thinking creature.
Upon this slender foundation, Decartes attempted to build his philosophy. How successful he was depends on your point of view but in philosophy, reaching a final goal is arguably less important than making important discoveries along the way and Descartes certainly did so. His discoveries are still discussed today.
As for the Cogito, the apparently safe foundation to knowledge that Descartes had promulgated, even this was called into doubt by Friedrich Nietzsche. Freddy, as he is affectionately known to many philosophers, was an odd character. For one thing he became insane but not before he had run amok through the philosophical world, turning it upside down. People are still evaluating his work today. If he didn’t actually kill the Cogito, he at least severely dented it.
He invented the following apparently fantastic scenario, strangely remininscent of Descartes’ demon; what if there is a cloud of disembodied thought floating around, among which there is the thought that these thoughts belong to a specific “I” which doesn’t actualy exist? A series of collections of thoughts each including the thought “These are my thoughts” would give the impression that an “I” existed where there was none. So much for the spurious certainty of the Cogito. Or “Boom! Boom!”, as Basil Fox might have said.
In an environment where only disembodied thoughts exist there are no “things”, “events” or “laws of nature”. Not even a thinking “I” whose thoughts they are. “We” can count on nothing. “Our” thoughts are mere delusions. Nothing that “we” think exists does exist. “We” can know nothing.
Does anyone believe this Nietzschean realm of disembodied thoughts exists and actually is what “we” think of as the world? Probably not. Not outside a secure mental institution, that is. I say that, not because I think you have to be mad to think like that but because I think that if you did think like that you would probably go mad.
So what do we do now – forget the whole nightmare and get back to working out what happens when you fall into a black hole or whether it is feasible to build a manned station on the moon? Or should we be worrying about Mad Old Freddy’s mad old ideas?
Like the Buddha, I think a path in between the two extremes is the best. If we surrender to the fear that all is delusion, then we might as well give up trying to learn anything and not bother to get up in the morning (or at any other time). On the other hand, if we are too confident and are not ready to revise our ideas or to abandon them if new evidence throws up grave problems, then we are again heading into a world of delusion and disillusion.
We must go forward boldly but with caution and a touch of humility. The more evidence we accumulate, the more consistent it appears and the more logical the theories we build to fit it all together, the greater our confidence that there must be some reality behind what we are learning and that it must bear some passing resemblance to the portrait we are making of it.
Science and philosophy are cumulative systems of knowledge; they never claim to be complete or perfect, just a little bit more complete than previously and even then, ready to go back and think again. That is our best guarantee that we really are coming to grips with reality. Our knowledge of reality is like the sea: the further in you go, the deeper it gets. No once-and-forever pronouncement of the “truth” can keep pace with what we are learning about the world. Grow or die.