The strength of such workers is that they base themselves on the experience and discoveries of the past, and, by artificial but convenient limitation of outlook, achieve practical results. But they are not satisfied with results actually achieved--they forget their limitations--and, by a gigantic system of extrapolation from what has been done, try to infer what is going to be done; their device being to anticipate and speak of what they hope for, as if it were already an accomplished fact. Some of the assumptions or blind guesses made by men of this school are well illustrated by an exposition in _The Hibbert Journal_ for July 1916, where an able writer states the main propositions of Scientific Materialism thus:-- 1. The law of universal causation; 2. The principle of mechanism--_i.e._ the denial of purpose in the universe and all notions of absolute finalism or teleology; 3. The denial that there exists any form of 'spiritual' or 'mental' entity that cannot be expressed in terms of matter and motion. These appear to be its three propositions, and they are formulated by the exponent "as being of the first importance in the representation of materialistic thought." Now proposition 1 is common property; materialistic thought has no sort of exclusive right over it; and to claim propositions 2 and 3 as corollaries from it is farcical. Taking them as independent postulates--which they are--all that need be said about proposition 2 is that a broad denial always needs more knowledge than a specific assertion, and it is astonishing that any sane person can imagine himself to know enough about the Universe as a whole to be able complacently to deny the existence of any "purpose" in it. All he can really mean is that scientific explanations must be framed so as to exhibit the immediate means whereby results in nature are accomplished; for whether, or in what sense, they are first or simultaneously conceived in a Mind--as human undertakings are--is a matter beyond our scientific ken. Thus Darwinian and Mendelian attempts to explain how species arise, and how inheritance occurs, are entirely legitimate and scientific. For our experience is that every event has a proximate cause which we can investigate. Of ultimate causes we as scientific men are ignorant: they belong to a different region of inquiry. If the word "denial," therefore, in the above proposition is replaced by the phrase "exclusion from practical scientific attention," I for one have no quarrel with clause 2; for it then becomes a mere self-denying ordinance, a convenient limitation of scope. It represents Policy, not Philosophy.