The attempted reconstructions are based on views which in their most definite form are regarded as characterizing the historical or diffusionist school of anthropologists. In contro versial opposition are those to whom the term "evolutionists" has unaccountably become attached. Whilst the extreme diffusionist regards the independent origin and development of similar or identical methods, artefacts, beliefs and customs, as having been so infrequent as to be of negligible significance, the extreme evo lutionist is supposed to postulate independent evolution as an ever-ready explanation of such similarities. It is not probable, however, that there is any evolutionist who denies the occurrence of diffusion, and there is certainly no diffusionist who denies the occurrence of evolution. There is, too, the belief that the whole controversy is futile.
The test question is that of the cultures of the Indians of America. There are some anthropologists who are prepared to regard diffusion as an acceptable and far-reaching explanation within the limits of the Old World and the New, respectively, but who look upon the culture of the American Indians as to all in tents and purposes indigenous. This view involves the acceptance of a great number of difficult cases of independent origin and parallel or converging development.
In this enquiry much depends on whether we regard man's inventive powers as originative in char acter, based upon a far-seeing anticipation of ways and means as well as ends, or as an opportunism which ranges from the casual to the persistent according to circumstances. Under modern civilized conditions there is a constant striving, on the part of a small number of individuals, after discovery and invention. Even when the unexpected happens and is seized upon, there is some end in view, though it may be different from that eventually achieved. The world-wide literature of science, modern knowledge of the properties of materials, and of chemical and physical forces, combined with the possession of a great variety of tools and machines, are apt to lead us to conceive of the inventor as a creator rather than an adapter and improviser. Giant strides are apparently made, but they are in reality due to the summation of a number of much smaller steps; judgment is often confused, also, by the fact that a simple discovery may have important results, the discovery being judged by its consequences, and not by its own intrinsic simplicity. The fact that, as is the case with most modern advances, it could not have been made without elaborate apparatus or refined technique, may be of historical interest, but this does not take it out of the category of the dis coveries that man has been making since his career began. In short, the existing social and material conditions enable the civilized inventor to place himself in the way of receiving sug gestions that can only reach him by way of methods and appli ances that are themselves the end-results of a prolonged process of gradual evolution. Civilized man has, moreover, become con vinced that nearly all things are possible, and that the unknown is not only a territory to be explored without fear, but with hope of great reward. He is an opportunist, pursuing discovery and
invention by way of experiment to the furthering of directional aims, and his advantages over his early predecessors are due to his social and material heritage, and not to intellectual superiority. We can scarcely doubt that under conditions that favoured the accumulation of knowledge, and that provided opportunities and incentives to the discoverer and inventor, there have been in all the higher human cultures, individuals, relatively few in number, who have adopted such directional methods as their knowledge and material equipment allowed. But the ancient civilizations were themselves based upon the prior evolution of a grade of culture that rendered their foundation possible, and only when these had become well established were the conditions for the emergence of directional invention fulfilled. Even then the limi tations of knowledge and the inhibitions of habit, prejudice and superstition, made progress incomparably slower than it is in our own times. Amongst uncivilized peoples, perceptible ad vance has probably been made only when racial contacts and im pacts, great changes in environment, or discoveries which opened up new possibilities—such as those which led to agriculture and metal-working respectively—raised men out of the stagnation due to unchanging environment and a static condition of know ledge. There was new material to work upon, and attempts to apply the old methods were met by unexpected reactions on the part of the material or appliances used.
If we regard directional invention as characteristic of peoples living under civilized conditions, it is necessary to enquire how progress was made before civilization was established. If it could be said in 1927 that "most discoveries in physics arise from some experimental fact discovered more or less accidentally" (Presidential address [by Sir James B. Hen derson] to the engineering section of the British Association for the Advancement of Science, 1927), it is not unreasonable to ascribe to chance the discoveries of early man. It can hardly be supposed that he experimented with stones in order to produce fire, before he had observed the production of sparks by a chance percussion; or that he took to testing the germinating power of seeds, because he felt the need of a more reliable f ood-supply; nor did he invent the blow-tube because he wanted something with which to shoot pellets or darts. He discovered accidentally that certain results followed certain actions, and in many cases the means came to hand and the end was achieved before the need was realized. There must have been innumerable instances of failure to recognize that a useful discovery was within reach, and the means and the end and the need alike remained unknown. Clay may have hardened in the fire, and copper melted, many times in vain.