That essay is one of the very important reference items for our collection, and you ought to get a copy for your files - the same idea (that witnesses are believed truthful when giving evidence for capital crimes, but not when giving evidence on miraculous events) is argued elsewhere in Chesterton's writing; Jaki examines it in his God and the Sun at Fatima. (We might add this question of "miracle" to our list of research topics, if we have not already.)
Then they [agnostioc Victorians] began to hunt and destroy the Sea-Serpent with all the old battered weapons of Early Victorian doubt: the weapons they had already blunted against much more important things. First they used, as sceptics always use, the anti-democratic argument. They said that the captains and seamen were coarse, unlettered men who could not be trusted on a point of so much delicacy as a sea-monster. They would not believe in a marine serpent on the evidence of uneducated men. They would hang a man on the evidence of uneducated men. They would get a citizen jailed and flogged on the bare word of some policeman who paved the police-court with his fallen aitches. But when a seafaring man said he had seen something fifty feet long which he had no earthly motive for pretending he had seen - then they suddenly remembered that he had never had a university education. He had never received that exact philological finish, that delicate turn of style and centrality of taste which enables a man to know whether something about the size and shape of the Scotch Express is going past his ship or not.
[GKC ILN Oct 21 1911 CW29:175-6]
For some reason, which I dare not go into just now, this topic seems to call forth a good deal of humour, even from the serious student of the topic. I note it in both Chesterton and Jaki. Perhaps because the issue is comical - perhaps because reality is comical - since the truth is so often unexpected:
The most incredible thing about miracles is that they happen.For example, in that ILN essay I just quoted, we have one of the must hilarious bits of "animal humour", yet which addresses the topic directly:
[GKC "The Blue Cross" in The Innocence of Father Brown]
When first the giraffe was described by travellers it was treated as a lie. Now it is in the Zoological Gardens; but it still looks like a lie. If few save stray travellers had seen the thing, and if the scientists (for some muddle-headed reason of theirs) had decided to doubt it, it would have been quite easy for them to explain every alleged appearance in the same way.Yes... and this same thing comes up in Father Jaki's writing...
[GKC ILN Oct 21 1911 CW29:176]
The defense of miracles done with an eye on physics should include a passing reference to meteorites. Characteristic of the stubborn resistance of scientific academies to those strange bits of matter was Laplace's shouting, "We've had enough such myths," when Pictet, a fellow academician, urged a reconsideration of the evidence provided by "lay-people" as plain eyewitnesses. Laymen were they in the sense that they had no telescopes, no training in celestial mechanics, no knowledge of trajectories, azimuth, right and left ascension. But they could register with absolute certainty that a fiery body had just hit the ground nearby and could unerringly distinguish its still warm stony remains as something not belonging to the soil around it. That such a kind of witnessing stands in its own right was the point recognized by a doctor on being confronted with the objection of a coüeague who insisted that the wide-open fracture below the left knee of Pieter De Rudder (1822-1898), the subject of possibly the most startling cure related to Lourdes, could not be accepted for a fact because the two ends of the broken bone protruding through the skin had not been certified by a medical commission. The reply of that rightly indignant physician, "it does not take a tailor to see that a coat is full of holes," contains an instructiveness that is practically inexhaustible.
[SLJ Miracles and Physics 94-95, emphasis added]