What modern people want to be made to understand is simply that all argument begins with an assumption; that is, with something that you do not doubt. You can, of course, if you like, doubt the assumption at the beginning of your argument, but in that case you are beginning a different argument with another assumption at the beginning of it. Every argument begins with an infallible dogma, and that infallible dogma can only be disputed by falling back on some other infallible dogma; you can never prove your first statement or it would not be your first. All this is the alphabet of thinking. And it has this special and positive point about it, that it can be taught in a school, like the other alphabet. Not to start an argument without stating your postulates could be taught in philosophy as it is taught in Euclid, in a common schoolroom with a blackboard. And I think it might be taught in some simple and rational degree even to the young, before they go out into the streets and are delivered over entirely to the logic and philosophy of the Daily Mail.
Much of our chaos about religion and doubt arises from this--that our modern sceptics always begin by telling us what they do not believe. But even in a sceptic we want to know first what he does believe. Before arguing, we want to know what we need not argue about. And this confusion is infinitely increased by the fact that all the sceptics of our time are sceptics at different degrees of the dissolution of scepticism.
Now you and I have, I hope, this advantage over all those clever new
philosophers, that we happen not to be mad. All of us believe in St. Paul's
Cathedral; most of us believe in St. Paul. But let us clearly realize this
fact, that we do believe in a number of things which are part of our
existence, but which cannot be demonstrated. Leave religion for the moment
wholly out of the question. All sane men, I say, believe firmly and
unalterably in a certain number of things which are unproved and unprovable.
Let us state them roughly.