Am I a sceptic? My immediate reaction is to deny this – after all it means that I am only too ready to reject the many statements of claimed truth which come to my attention. Or does it? Scepticism has been a central issue of philosophical discussion for over 2000 years – and it continues.
Socrates was a sceptic. But he would describe it as his teaching that we can never be certain about the truth. In fact we never establish the truth but, through debate and examination, we may hope to get closer to it. Flash through a few hundred years to the 18th century and we arrive at David Hume. He taught that all our experiential knowledge is no more than concepts in our brains. If, for instance, I am drinking a glass of wine, my view of it is an impression in my brain; our recognition of colour, tactility or flavour are all aspects of these internal impressions. I have no way of proving that it is an actual, existing object. He denied the connection between cause and effect: we know, for instance how billiard balls act on one another, but we have no way of proving that this is causal. He had no time for morality: we have only observed the outcomes of our decisions: labelling them as moral or immoral simply has no meaning. There is an “is” but there is no “ought”.
I am tempted to put this down to his Jesuit education – which puts much effort into asking questions and requiring demonstrations of evidence. He studied at the Jesuit college of La Flèche in France. Unfortunately René Descartes (17th century) was the great champion of truth and he went to La Flèche too. His starting point, after much thinking, was je pense donc je suis = I think therefore I am – often quoted as cogito ergo sum. On this, his solid brick of truth, he built his philosophy.
Ironically science is essentially sceptical. Its conclusions are always in principle open to new evidence or new procedures. We might, for instance, confidently state that water boils at 100 degrees centigrade – only to discover later that the figure actually changes according to altitude.
Metaphysical truths are a different matter. In this case meta means “beyond”. Since they are beyond the physical we cannot demonstrate them physically. Or for that matter in any other way. The phrase “I know that God exists” is strictly nonsense. We can say that we hold that God exists or that we believe that God exists. We can of course refer to arguments of various kinds which lead us towards belief but our conclusion is a personal decision.
Aquinas approaches it in a different way. He demonstrates that it is necessary to have a first cause and this, he says, is what we call God. So he goes from the natural to the supernatural. Without disagreeing with him, I prefer to approach this differently. I am sure of the existence of love and this, I claim, is what we call God.