William Donaldson's Week In which I tell Mr Johnson what to do

THIS space will be blank today (I had intended to discuss John Elway's present inability to complete as many touchdown passes for the Denver Broncos as for the opposition) due to a last-minute invitation from the editor of the Spectator.

He has asked me to reply to an article by Paul Johnson in which he argues - asserts, at least - that Sir Karl Popper has been the only philosopher this century who has told us what to do (most crucially, has told Lady Thatcher and Mr Johnson what to do) instead of engaging in academic fiddle-faddle.

Since my field is the mind/body problem rather than the philosophy of science (or 'stinks', as Mr Johnson calls it in an excellent parody of Telegraph group polemicists) and since I would have wished to read the relevant texts as carefully as Mr Johnson must have done before making such a large claim, I was reluctant at first to embark upon such a substantial undertaking.

It then occurred to me that, due to the two-way nature of primitive logic (if the conclusion of a valid syllogism is self-evidently untrue one or both of its premises are thereby refuted), it might be amusing - rather than obviously facetious - to argue that, precisely because Lady Thatcher admires them, Popper's arguments must be false.

I therefore put other current enterprises on hold - this column, El Independo, How To Tell If Your Parents Aren't On Drugs (they get rat-arsed once a week and beat each other up) - while I re- read all of Sir Karl's published books and papers.

Mr Johnson starts by dismissing the work of every other 20th-century philosopher - Russell, Wittgenstein, Ayer (Mr Johnson relies on Viscount Hailsham as his authority against logical positivism) - and his arguments, not that he offers any, were easily disposed of.

The charge against Wittgenstein ('The message I got from Wittgenstein was that nothing can be proved at all') might, since Wittgenstein believed that there are no real philosophical problems and that the pseudo-problems can be solved, have been levelled more successfully against Popper's deep scepticism. Further, and allowing Carnap (the most influential of the logical positivists) to stand in for Ayer, Johnson's remarks against Russell, whom Popper revered, and the logical positivists ('For Ayer, many of the great moral and aesthetic truths are mere 'value judgements' and therefore meaningless') could best be shown up as merely ignorant by quoting Popper himself (Conjectures And Refutations, 1963).

'I found in Carnap a thinker utterly absorbed in his problems, and eager to listen to criticism. Indeed, among many other characteristics which Carnap shares with Bertrand Russell - whose influence on all of us was greater than anyone else's - is his intellectual courage in changing his mind.'

It was worth pointing out, too, I thought, that Ayer, in a rare excursion into moral philosophy (The Central Questions of Philosophy, 1973) put paid to the idea that he was a supporter of moral relativism.

'A moral code cannot be founded on authority, on metaphysics, on science or on empirical matters of fact. This does not mean that we have to regard every moral standpoint as equally correct. In holding a moral principle, one regards it as valid for others besides oneself, whether they think so or not. The subjectivist is content to say that these are his moral principles and leave it at that, whereas the believer in absolute values wants to say that his moral judgements are objectively true. Since his only criterion of their truth is his own intuition, the difference is negligible.'

Turning to Popper's philosophy of science, I dealt only briefly with the merits of falsifiability against verificationism, since I judged that the arguments involved would be too technical for Spectator readers. I did point out, however, that criticisms of the verification principle, by, among others, Hempel, Goodman and Church, have, if slightly modified, posed the same threat to Popper's principle of falsifiability; further, that falsifiability is, in any event, an insufficient criterion of the scientific nature of a theory.

Instead, I argued that Popper's own admission that rationalism in science (ie falsifiability) can only be advocated through an ethical choice ('I freely admit that in arriving at my proposals I have been guided, in the last analysis, by value judgements and predilections' - The Logic of Scientific Discovery, 1934) yields this unfortunate conclusion: that for Popper, rationalism is ultimately a matter of irrational faith; that the leading advocate of a critical approach to problems bases his whole philosophy on a premise he admits is indefensible.

Finally, I concluded with Putnam (What is Realism?, 1976) that, because of Popper's hostility to justificationism (false theories and well- confirmed theories will both have zero probability), he failed not only to construct a viable system of knowledge without justication but also to understand the role science plays in human life generally.

'When a scientist accepts a law, he is recommending to others that they rely on it. Only in wrenching science out of the context in which it arises - the context of men trying to change and control the world - can Popper even put forward his peculiar views on induction. Ideas are not just ideas; they are guides to action.'

Satisfied that I had shown, against Johnson, that Popper failed to deliver practical formulae, I yet decided to check the matter out with Bryan Magee.

'I can't agree with you,' said Mr Magee. 'It's true that Popper wasn't interested in the analysis of moral concepts. However, because he was concerned with real problems, he has influenced the thinking of plain men. Johnson is merely a knockabout journalist, but there is some truth in what he says.'

A whole week's work down the drain. Never mind. I do, after all, seem to have a column - and still up my sleeve is my assertion that, compared with Dan the Man, John Elway is a big girl's blouse.