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A PINCH OF SALT
Probably I have become unusually cautious of late about accepting offhand all I read in print on subjects of natural history. I take much of it with a liberal pinch of salt. Newspaper reading tends to make one cautious—and who does not read newspapers in these days? One of my critics says, apropos of certain recent strictures of mine upon some current nature writers, that I discredit whatever I have not myself seen; that I belong to that class of observers "whose view-point is narrowed to the limit of their own personal experience." This were a grievous fault if it were true, so much we have to take upon trust in natural history as well as in other history, and in life in general. "Mr. Burroughs might have remembered," says another critic discussing the same subject, "that nobody has seen quite so many things as everybody." How true! If I have ever been guilty of denying the truth of what everybody has seen, my critic has just ground for complaint. I was conscious, in the paper referred to,[4] of denying only the truth of certain things that one man alone had reported having seen,—things so at variance not only with my own observations, but with those of all other observers and with the fundamental principles of animal psychology, that my "will to believe," always easy to move, balked and refused to take a step.
[4] Atlantic Monthly, March, 1903.
In matters of belief in any field, it is certain that the scientific method, the method of proof, is not of equal favor with all minds. Some persons believe what they can or must, others what they would. One person accepts what agrees with his reason and experience, another what is agreeable to his or her fancy. The grounds of probability count much with me; the tone and quality of the witness count for much. Does he ring true? Is his eye single? Does he see out of the back of his head?—that is, does he see on more than one side of a thing? Is he in love with the truth, or with the strange, the bizarre? Last of all, my own experience comes in to correct or to modify the observations of others. If what you report is antecedently improbable, I shall want concrete proof before accepting it, and I shall cross-question your witness sharply. If you tell me you have seen apples and acorns, or pears and plums, growing upon the same tree, I shall discredit you. The thing has never been known and is contrary to nature. But if you tell me you have seen a peach tree bearing nectarines, or have known a nectarine-stone to produce a peach tree, I shall still want to cross-question you sharply, but I may believe you. Such things have happened. Or if you tell me that you have seen an old doe with horns, or a hen with spurs, or a male bird incubating and singing on the nest, unusual as the last occurrence is, I shall not dispute you. I will concede that you may have seen a white crow or a white blackbird or a white robin, or a black chipmunk or a black red squirrel, and many other departures from the usual in animal life; but I cannot share the conviction of the man who told me he had seen a red squirrel curing rye before storing it up in its den, or of the writer who believes the fox will ride upon the back of a sheep to escape the hound, or of another writer that he has seen the blue heron chumming for fish. Even if you aver that you have seen a woodpecker running down the trunk of a tree as well as up, I shall be sure you have not seen correctly. It is the nuthatch and not the woodpecker that hops up and down and around the trees. It is easy to transcend any man's experience; not so easy to transcend his reason. "Nobody has seen so many things as everybody," yet a dozen men cannot see any farther than one, and the truth is not often a matter of majorities. If you tell me any incident in the life of bird or beast that implies the possession of what we mean by reason, I shall be very skeptical.
Am I guilty, then, as has been charged, of preferring the deductive method of reasoning to the more modern and more scientific inductive method? But I doubt if the inductive method would avail one in trying to prove that the old cow really jumped over the moon. We do deny certain things upon general principles, and affirm others. I do not believe that a rooster ever laid an egg, or that a male tiger ever gave milk. If your alleged fact contradicts fundamental principles, I shall beware of it; if it contradicts universal experience, I shall probe it thoroughly. A college professor wrote me that he had seen a crow blackbird catch a small fish and fly away with it in its beak. Now I have never seen anything of the kind, but I know of no principle upon which I should feel disposed to question the truth of such an assertion. I have myself seen a crow blackbird kill an English sparrow. Both proceedings I think are very unusual, but neither is antecedently improbable. If the professor had said that he saw the blackbird dive head first into the water for the fish, after the manner of the kingfisher, I should have been very skeptical. He only saw the bird rise up from the edge of the water with the wriggling fish in its mouth. It had doubtless seized it in shallow water near the shore. But I should discredit upon general principles the statement of the woman who related with much detail how she and her whole family had seen a pair "of small brown birds" carry their half-fledged young from their nest in a low bush, where there was danger from cats, to a new nest which they had just finished in the top of a near-by tree! Could any person who knows the birds credit such a tale? The bank-teller throws out the counterfeit coin or bill because his practiced eye and touch detect the fraud at once. On similar grounds the experienced observer rejects all such stories as the above. Darwin quotes an authority for the statement that our ruffed grouse makes its drumming sound by striking its wings together over its back. A recent writer says the sound is not made with the wings at all, but is made with the voice, just as a rooster crows. Every woodsman knows that neither statement is true, and he knows it, not on general principles, but from experience—he has seen the grouse drum.
Birds that are not flycatchers sometimes take insects in the air; they do it clumsily, but they get the bug. On the other hand, flycatchers sometimes eat fruit. I have seen the kingbird carry off raspberries. All such facts are matters of observation. In the search for truth we employ both the deductive and the inductive methods; we deduce principles from facts, and we test alleged facts by principles.
The other day an intelligent woman told me this about a canary-bird: The bird had a nest with young in the corner of her cage; near by were some other birds in a cage—I forget what they were; they had a full view of all the domestic affairs of the canary. This publicity she evidently did not like, for she tore out of the paper that covered the bottom of her cage a piece as large as one's hand and wove it into the wires so as to make a screen against her inquisitive neighbors. My informant evidently believed this story. It was agreeable to her fancies and feelings. But see the difficulties in the way. How could the bird with its beak tear out a broad piece of paper? then, how could it weave it into the wires of its cage? Furthermore, the family of birds to which the canary belongs are not weavers; they build cup-shaped nests, and they have had no use for screens or covers, and they never have made them. Just what was the truth about the matter I cannot say, but if we know anything about animal psychology, we know that was not the truth. It is always risky to attribute to an animal any act its ancestors could not have performed.
Again, things are reported as facts that are not so much contrary to reason as contrary to all experience, and with these, too, I have my difficulties. A recent writer upon our wild life says he has discovered that the cowbird watches over its young and assists the foster-parents in providing food for them—an observation so contrary to all that we know of parasitical birds, both at home and abroad, that no real observer can credit the statement. Our cowbird has been under observation for a hundred years or more; every dweller in the country must see one or more young cowbirds being fed by their foster-parents every season, yet no competent observer has ever reported any care of the young bird by its real parent. If this were true, it would make the cowbird only half parasitical—an unheard-of phenomenon.
The same writer tells this incident about a grouse that had a nest near his cabin. One morning he heard a strange cry in the direction of the nest, and taking the path that led to it, he met the grouse running toward him with one wing pressed close to her side, and fighting off two robber crows with the other. Under the closed wing the grouse was carrying an egg, which she had managed to save from the ruin of her nest. The bird was coming to the hermit for succor. Now, am I skeptical about such a story, put down in apparent good faith in a book of natural history as a real occurrence, because I have never seen the like? No; I am skeptical because the incident is so contrary to all that we know about grouse and all other wild birds. Our belief in nearly all matters takes the line of least resistance, and it is easier for me to believe that the writer deceived himself, than that such a thing ever happened. In the first place, a grouse could not pick up an egg with her wing when crows were trying to rob her, and, in the second place, she would not think far enough to do it if she had the power. What was she going to do with the egg? Bring it to the hermit for his breakfast? This last supposition is just as reasonable as any part of the story. A grouse will not readily leave her unfledged young, but she will leave her eggs when disturbed by man or beast with apparent unconcern.