On Logic and Lunacy

THE idea of logic is so entirely lost in this phase of philosophical history, that even those who invoke it do so rather as the Athenians once invoked the Unknown God, or the men of the Dark Ages retained a dim respect for Virgil as a conjurer. The very people who say, ‘be logical’, will generally be found to be quite illogical in their own notion of logic. One of the last men who understood logic in its full and impartial sense, died only lately: the late William Johnson of King’s College, Cambridge; one of the finest minds of the age and an exact measure of the modern contrast between notability and notoriety. I mean that somehow the glory has departed from glory, and the first men of the time are often the last men to be advertised or even adequately admired. He was as incapable of intellectual injustice as of infanticide; and while he and I differed about a thousand things, even if I had regarded his view as ultimately leading to falsehood, I should always have known that it was free from the faintest tinge of fallacy. If there had been any weed of weak logic in his own argument he would have torn it up with as much joy as any weed in the garden of the enemy. For he liked that sort of weeding as an amusement and an art — a sort of art for art’s sake. And when I wander in the jungle of journalistic nonsense in which we all live to-day, his memory again and again returns.

Let us begin with a trifle that does not matter in the least. He loved to argue about trifles that do not matter in the least. Some journalist the other day shook the foundation of the universe and the British Empire by raising the question of whether a girl ought to smoke a cigar. But what I noted about his, and about the hundred eager correspondents who pursued this great theme, was that they wrote again and again some such sentence as this: ‘If you like a girl to smoke a cigarette, why can’t you be logical and like her to smoke a cigar?’ Now I do not care an ounce of shag whether she smokes a cigarette or a cigar or a corn-cob pipe or a hubble-bubble, or whether she smokes three cigars at once, or whether she is an Anti-Tobacco crank. But it is none the less true that when a man writes that sentence telling us to ‘be logical’, he shows that he has never even heard of the nature of logic. He might just as well write: ‘You like the look of a horse; why won’t you be logical and like the look of a hippopotamus?’ The only answer is, ‘Well, I don’t; and it is not illogical, because it does not in any way invade the realm of logic. A man has a perfect right to say that he likes the look of one thing and does not like the look of another thing; or even that he likes the look of a smaller thing, but does not like the look of a larger but somewhat similar thing. It is all a question of liking; and not in the least a question of logic. There is no logical compulsion upon him whatever to go on from the smaller to the larger and like them both. The man who uses this phrase attaches some queer particular meaning to the word ‘logical’; something that is dimly adumbrated in the words, ‘extremist’ or ‘going the whole hog’. But if my appetite is so small that I only require half a hog for breakfast, I am not any less of a logician because I refuse to eat the whole hog for breakfast. The obligation to eat the whole hog, if it exists, must be a mystical or moral or transcendental obligation; but it is not a logical obligation. It is not logical, because it has not been deduced from any premises; it has simply been stated without reference to any premises.

And that is what is the matter with the modern man who says, ‘be logical’. He cannot take his own advice, and therefore he cannot state his own first principles. But though his logic is nonsense as he states it, it does refer to some first principles if he could only state them. It all depends on the reason for approving of cigarettes or cigars or girls or any other strange creatures. What he really means, at the back of his muddled modernistic mind, is some thing like this: ‘If I approve of Jennifer smoking a cigarette because Jennifer can jolly well do anything she likes, and does, then it is illogical in me to object to her liking a cigar; or for that matter an opium-pipe or a pint of laudanum or a bottle of prussic acid.’ And this statement would really be quite logical, because the logical reason is given. Or if he said, ‘It is my first principle that women may do anything that men do; therefore I am bound in logic to pass the cigars to my daughter as much as to my son,’ then that also is perfectly reasonable as the application of a stated principle. But to say that a man is bound in logic to like a cigar as much as a cigarette whether in his own mouth or that of his maiden aunt or his maternal grandmother, is stark staring unreason; and shows that the speaker is entirely illogical in dealing with the two ideas of liking and logic.

This half superstitious veneration for logic, combined with a complete misunderstanding of it, is very common in those popular works of fiction which are the joy of my existence; the crime novels and the police romances and the rest. There is a queer notion that the detective, who is distinguished from all human beings by having the gift of reason, is bound in logic not to like anything or anybody. Even Sherlock Holmes (the friend of my childhood to whom I shall always pay a tribute of piety) is described somewhere, I think, as being incapable of falling in love because of his logical nature. You might as well say that he could not be expected to have much appetite for lunch, because of his proficiency in mathematics. There is nothing intrinsically illogical in having affections or admirations or appetites, so long as we recognize them reasonably as what they are. But the romantic tradition, as it exists in all the romances, is that the logician cannot be romantic. It may be remarked that the word ‘cold’ will always be found coupled with the word ‘logical’; I imagine the printers keep such words together in one block of type. But the cold logician, though be must not be romantic, is almost entirely a creature of romance. As a matter of fact and experience, most of the very logical people I have known have been very warm-blooded, affectionate or enthusiastic people. Most of the very good debaters were very warm debaters. Some of the closest reasoners in history were men of the most enthusiastic convictions; like St. Thomas Aquinas or the great French preachers and orators. The truth is, I think, that it was because the English were originally taught to have a prejudice against logic, that even when they half overcame the prejudice, there remained something alien in the admiration. They could be brought to feel a sort of awe in the presence of a really reasonable person; as if he were a sort of monster. The fact that a man could think could only be explained on the hypothesis that he was a Martian or the Man in the Moon; that he was a Clockwork Man; that he was The Thinking Machine. They began by thinking that reason is inhuman; and only gradually conceded that it is superhuman.

Is it not about time somebody preached the older doctrine; that reason is human? Is there not some thing to be said for those medieval Schoolmen and antiquated sages, who held that man is a rational animal; and even more rational than the other animals? The modern experiment of first sneering at logic for not being a practical thing, and then timidly praising it for being a priggish thing, seems to have resulted in the general loss of it as a normal function of the mind. It is as if the same Victorian English had supported their railway-trains by forbidding anybody to walk; and then, when all human limbs were paralysed, had deified two or three athletes as gods because they had the power of walking. Logic is as normal as legs; but legs can be neglected as well as logic. All that is needed is a little ordinary training and practice; the knowledge that inferences rest on their first principles, as men rest on their feet. But without it the world seems to be drifting into an intellectual dissolution and destruction, which is at its very wildest when some wild voice shrieks out of the chaos; ‘Be logical’. This strange cry apparently means that you cannot stroke a cat without stroking a tiger; or that you are bound to wish the house was on fire because you sit by the fireside.

~G.K. Chesterton: collected in All is Grist, XVII. (first published 1931)

Logic, by Lucca della Robbia.
Stone, c. 1437; Museo dell'Opera del Duomo, Florence