"The idols of the market are the most troublesome of all; those, namely, which have entwined themselves around the understanding from the associations of words and names. "There arises from a bad and unapt formation of words a wonderful obstruction to the - BACON. mind.". "Language being accommodated to the prænotions of men and the uses of life, it is difficult to express therein the precise truth of things, which are so contrary to our prænotions. But to one of due attention, and who makes my words an occasion of his own thinking, I conceive the whole to be very intelligible; and when it is rightly understood I scarce doubt but it will be assented to."— BERKELEY. LECTURE VIII DARWIN, AND THE ORIGIN OF SPECIES THE aim of this lecture is to show that most of the post-Darwinian criticism of natural selection might have been avoided if Darwin and Wallace, and they who have come after, had not been unconsciously led to make use of words and forms which have since outlived their meaning. I do not allude to the assertion so often made that natural selection personifies nature, and attributes to it the power of deliberate choice; for no one who thinks for himself can attach any such meaning to Darwin's words, or be misled by them. The Duke of Argyll, indeed, says Darwin's work is "essentially the image of mechanical necessity concealed under the clothes and parading in the mask of mental purpose," since natural selection "personifies an abstraction." If the roses in a garden differ among themselves in power to resist cold, and the more tender ones are found dead after a hard winter, the Duke of Argyll may, if he sees fit, charge him who says the toughest ones have been selected, with infantile belief in the personal agency of Jack Frost, but I cannot believe thoughtful men will support him. If living things differ among themselves, and if those which survive the struggle for existence are the ones which might have been expected to survive, natural selection is a fact; and while opinions as to the value of this fact may differ, the name we call it by matters little. One of the most familiar criticisms of natural selection is that, since it does not produce, but only preserves, the fitness which exists, it does not show why there should be any fit to survive, but only why the unfit are exterminated. "Natural selection," says Darwin ("Origin," p. 75), "acts only by the preservation and accumulation of small inherited modifications, each profitable to the preserved being." This has seemed, and still seems, to many, a valid reason for questioning its value as a scientific explanation of the origin of species; although not one who makes Darwin's words an occasion of his own thinking need be perplexed by this criticism. If peas are rolled down an inclined board, the largest go fastest, the smallest slowest, and the round ones go straight to the bottom, while the irregular ones run off the sides. What if one were to assert that this device can have no value as a means for sorting peas until we know what makes one pea large and another small, one round and another irregular? Yet this is, in effect, asserted by those who declare that natural selection has no value as an explanation of the origin of species, because it does not show why there should be anything useful to select. Without knowing why one horse is more fleet than another, or even why horses exist, breeders have increased the speed of horses by breeding from the most fleet; just as a pack of wolves may increase it in nature by destroying, generation after generation, all the horses they can run down. If at every stage in the ancestry of horses there has been need for greater speed, natural selection accounts for the whole history of this power, and even for the first vague beginnings of locomotion in sedentary or floating animals, which may have found shelter from their enemies, or more abundant food, by those slight changes of place which may, at first, have been the incidental result of changes of shape. While it is obvious that a useful quality must exist before it can be useful, and before it can be influenced by selection, and while no Darwinian holds natural selection to be an ultimate explanation of fitness, all admit that horses do differ among themselves in speed, and that each may reasonably be expected to be more like its parents in speed than like a horse selected at random. As no one disputes the existence of these prerequisites to selection, the statement that selection could not act unless they existed is childish. I have tried to show, page 178, that the work of Darwin and Wallace teaches that the only path in which we can have any wellfounded hope of progress in the explanation of the origin of species |