Truth cannot be proved

Karl Popper, one of the very greatest thinkers of his, or any, age, was modest in expressing his philosophical findings. He prefaced his book The Open Society and its Enemies with a quotation from Edmund Burke which implied that all he, Popper, was trying to do was make a useful contribution to the greater work of more illustrious men:

“In my course I have known and, according to my  measure,
co-operated with great men, and I have never yet seen
any plan which has not been mended by the observations of
those who were much  inferior in understanding to the person
who took the lead in the business.”

Pay no attention to such modesty. His books The Logic of Scientific Discovery, The Poverty of Historicism, and The Open Society and its Enemies are among the most influential ever written. He revolutionized how men think about science and about truth itself. He explained with crystal clarity why all rigid ideology must fail and exposed the absurdity of utopianism in all its guises. He revealed with cultured precision the falsities at the core of communism and made men know that such falsities would ultimately lead to its collapse.

The Open Society was published in 1945 and The Poverty of Historicism in 1957. The fundamental flaws of revered philosophers such as Plato, Hegel and Marx were exposed more clearly than they had ever been and the whole world’s intellectual bias began to tilt a different way, gradually at first, overwhelmingly in the end. It took a little time for Popper’s lessons to be learnt and to take practical effect but he lived long enough to see the truths he had revealed those many years ago finally bear fruit in the rejection of rigid ideology and the collapse of communism in the Russian empire.

In the main, political philosophers have regarded the most important questions as being ‘Who should rule?’ and their differing philosophies seek to justify different answers – a single man, the well-born, the rich, the wise, the strong, the good, the majority, the proletariat. But Popper shows that the question itself is mistaken. Most importantly, the question ‘Where should sovereignty lie?’ rests on the assumption that sole and ultimate power must lie somewhere, but is that so? In most societies there are different and to some extent conflicting power centres, not one of which can get everything its own way. In the best societies power is and should be quite widely diffused. The question, ‘Yes, but where does it ultimately lie?’ eliminates before it is raised the possibility of control over rulers when that is the most important of all things to establish. The vital question is not ‘Who should rule?’ but ‘How can we minimize misrule?’ – both the likelihood of its occurring and, when it does occur, its consequences.

If you want to understand something of the intellectual impetus which led to the worldwide shift of political power which took place, read Karl Popper’s The Open Society and its Enemies and The Poverty of Historicism. And yet, as if his influence in that respect was not enough. Popper also transformed how men think bout the laws of science.

The accepted view was that scientific statements, being based on facts, are contrasted with statements of all other kinds – whether based on authority or emotion or tradition or religious diktat or speculation or prejudice or habit – as alone providing sure and certain knowledge. But, as Popper lucidly explains, this is not so. What we call our knowledge is of its nature provisional and will always be so. It is therefore a profound mistake to try to do what scientists and philosophers have almost always tried to do – prove the truth of a theory, or justify our belief in a theory, since this is to attempt the logically impossible.

A worrying aspect of recent scientific research is that important studies once thought to establish conclusive results – and on which, therefore, medical treatments or schemes of social improvement have been based – when revisited in new surveys of the same ‘facts’ now give rise to very different conclusions. Theories based on hard facts expected to stand the test of time all too easily melt into uncertain propositions when scrutinised anew. To give one of many examples, antipsychotic drugs tested very successfully on schizophrenics in the early 1990s – thus providing drug companies with some hugely profitable brand names – in new trials undertaken recently have been shown to be not at all as successful as the original trials seemed to show. These worrying findings are becoming so common that scientists have begun to give the phenomenon a name: ‘effect shrinkage’ or ‘decline effect.’ It simply means that what we may have thought was proved beyond a doubt is anything but. Thus do we find that truth seems impossible to prove and what is proved may not be true for very long.

All we can do in these circumstances, and this is of the highest importance, is to justify our preference for one theory over another at any given time. The traditional notion that the sciences are bodies of established fact is entirely mistaken. Nothing in any of the sciences is permanently established, nothing unalterable. If we are rational we shall always base our decisions and expectations on ‘the best of our knowledge,’ as the popular phrase so rightly has it, and provisionally assume the ‘truth’ of that knowledge for practical purposes, because it is the least insecure foundation available. However, we shall never lose sight of the fact that at any time new experience may show it to be wrong and require us to revise it.

In his autobiography Unending Quest Popper quotes a poem by the pre-Socratic philosopher Xenophanes which I have always kept near me in case I might get too arrogant about my opinions.

The gods did not reveal, from the beginning,
All things to us, but in the course of time
Through seeking we may learn and know things better.
But as for certain truth, no man has known it,
Nor shall he know it, neither of the gods
Nor yet of all things of which I speak.
For even if by chance he were to utter
The final truth, he would himself not know it:
For all is but a woven web of guesses.