It is undesirable to believe a proposition when there is no ground whatever for supposing it true

I am always dubious of Bertrand Russell and take anything by him with a grain of salt. He was indisputably brilliant, broadly and deeply learned and advanced human knowledge and insight. At the same time he was fully capable of cruelty and despicable treatment of his fellow man.

One of the challenges with Russell is that it is exceptionally difficult and requires great effort to dismantle his more extreme arguments. The piece parts are often rock solid, it is the final outcome and implied conclusion which are flawed.

However, he was brilliant and a magnificent writer. I do enjoy the opening paragraphs of his introduction to his 1928 book, Sceptical Essays.

I wish to propose for the reader’s favourable consideration a doctrine which may, I fear, appear wildly paradoxical and subversive. The doctrine in question is this: that it is undesirable to believe a proposition when there is no ground whatever for supposing it true. I must, of course, admit that if such an opinion became common it would completely transform our social life and our political system; since both are at present faultless, this must weigh against it. I am also aware (what is more serious) that it would tend to diminish the incomes of clairvoyants, bookmakers, bishops, and others who live on the irrational hopes of those who have done nothing to deserve good fortune here or hereafter. In spite of these grave arguments, I maintain that a case can be made out of my paradox, and I shall try to set it forth.

First of all, I wish to guard myself against being thought to take up an extreme position. I am a British Whig, with a British love of compromise and moderation. A story is told of Pyrrho, the founder of Pyrrhonism (which was the old name for scepticism). He maintained that we never know enough to be sure that one course of action is wiser than another. In his youth, when he was taking his constitutional one afternoon, he saw his teacher in philosophy (from whom he had imbibed his principles) with his head stuck in a ditch, unable to get out. After contemplating him for some time, he walked on, maintaining that there was no sufficient ground for thinking he would do any good by pulling the man out. Others, less sceptical, effected a rescue, and blamed Pyrrho for his heartlessness. But his teacher, true to his principles, praised him for his consistency. Now I do not advocate such heroic scepticism as that. I am prepared to admit the ordinary beliefs of common sense, in practice if not in theory. I am prepared to admit any well-established result of science, not as certainly true, but as sufficiently probable to afford a basis for rational action. If it is announced that there is to be an eclipse of the moon on such-and-such a date, I think it worth while to look and see whether it is taking place. Pyrrho would have thought otherwise. On this ground, I feel justified in claiming that I advocate a middle position.

Pyrrho would have been advocate of the precautionary principle.

There are matters about which those who have investigated them are agreed; the dates of eclipses may serve as an illustration. There are other matters about which experts are not agreed. Even when the experts all agree, they may well be mistaken. Einstein's view as to the magnitude of the deflection of light by gravitation would have been rejected by all experts not many years ago, yet it proved to be right. Nevertheless the opinion of experts, when it is unanimous, must be accepted by non-experts as more likely to be right than the opposite opinion. The scepticism that I advocate amounts only to this: (1) that when the experts are agreed, the opposite opinion cannot be held to be certain; (2) that when they are not agreed, no opinion can be regarded as certain by a non-expert; and (3) that when they all hold that no sufficient grounds for a positive opinion exist, the ordinary man would do well to suspend his judgment.

Were we to adopt these principles, news channels would fall silent, Twitter volumes would plummet, newspapers would have to return to local news to fill their pages, social media would be quieted. On the other hand, there would be a return to civility and a clearer progression of knowledge without so much heat and noise.