[The following review offers a negative opinion of The Philosophy of "As If," finding Vaihinger to be a "dull" writer and his ideas "obvious."]

This is a work that has had a great popular success in Germany, and is now gradually penetrating to foreign parts. It was first published in 1911 and is at present in its sixth edition; there is also a somewhat shorter Volksausgabe. Havelock Ellis, always alert for intellectual novelties, wrote an article about it four or five years ago, and there is already a small but active body of Vaihingeristas in England.

Like his master, Kant, and most other German philosophical writers (let us not forget the brilliant exceptions, Schopenhauer and Nietzsche!), Vaihinger is an extremely dull author, much given to long and complex phrases and to laborious repetitions. Nor has his translator, Mr. Ogden, done anything to rescue him from the labyrinth in which he wanders. On the contrary, the English version of the book is often even more vexatious than the original German. I point to one dreadful example: the translation of Vorstellungsgebilde as mental constructs. Is construct, then, an English noun? I doubt it. The noun, I believe, is structure. But even structure, in this place, would be clumsy, for what Vaihinger oviously means is image. I cite a typical sentence: "Er wäre es auch, wenn die Vorstellungsgebilde unmittelbare Abbilder des Seins wären." Ogden turns this into: "This would hold true even if our mental constructs were direct reflections of reality." Why not make it: "It would be so even if our mental images were direct images of reality?"

But despite all this pedantic fustian there is a clear idea in the book, and it is this: that man is so constituted that he cannot carry on the business of thinking without making frequent use of assumptions that are untrue, and known to him to be so—that he needs fictions as well as facts. Vaihinger makes a clear distinction between fictions and hypotheses—a distinction too often neglected by other philosophers. A hypothesis may not be true, but it is at least something that someone believes may become true: it is an attempt to approach the truth by a plausible guess. But a fiction is admittedly untrue, and its use is simply to get over an impassable place by throwing in logs and calling them solid rocks. In the jargon of the lawyers the former is a praesumptio juris and the latter a fictio juris. It is a praesumptio juris that when a man and his wife lose their lives together, as in a shipwreck, the wife dies first, as the weaker of the two. It may not be true in any given case, but it is at least probable in all cases, and so it is presumed to be true whenever the actual facts cannot be established. A legal fiction is quite different. It is an assumption that is admittedly not true: for example, that a glass of beer containing one half of one per cent plus one hundredth of one per cent of ethyl alcohol by volume is intoxicating.

In all fields of thought both hypotheses and fictions are constantly made use of. The former, as knowledge increases, often harden into laws, i.e., statements of actual fact. The atomic theory has shown some signs of doing that of late, though Vaihinger, writing of it so recently as 1911, treated it as if it were almost a fiction. Darwin's theory of natural selection began as a hypothesis, changed into a law, and is now a hypothesis again, with some chance of ending as a fiction. Adam Smith's notion that man in society is moved only by self-interest began as a working hypothesis, was turned into a law by uncritical enthusiasts, and is now generally held to be a pure fiction. But a fiction never becomes a hypothesis, though it may be transiently mistaken for one. Its essence is that it is known to be untrue. Its use is that it bridges the gap between two truths. Man can think only in logical patterns, and when there is a vacant space he must fill it as best he may, or stop thinking altogether.

It is difficult to understand why all this should have kicked up so much pother. What Vaihinger says, in the main, is quite obvious. True enough, he supports it with a great many concrete examples, taking from all the known sciences and pseudosciences, from mathematics to metaphysics. His erudition is genuinely colossal. But, as he himself frankly shows, his chief notion, that the use of fictions is necessary to thinking, was known to other men years and years ago; a large part of his volume, indeed, is given over to demonstrating the fact. Once he has demonstrated it, what follows? Nothing follows. The human mind, at its present stage of development, cannot function without the aid of fictions, but neither can it function without the aid of facts—save, perhaps, when it is housed in the skull of a university professor of philosophy. Of the two, the facts are enormously the more important. In certain metaphysical fields, e.g., those of mathematics, law, theology, osteopathy and ethics—the fiction will probably hold out for many years, but elsewhere the fact slowly ousts it, and that ousting is what is called intellectual progress. Very few fictions remain in use in anatomy, or in plumbing and gas-fitting; they have even begun to disappear from economics. Vaihinger's work is thus not a system of philosophy, in any true sense; it is simply a foot-note to all existing systems. Moreover, it is not a foot-note of much solid value. It is curious, but it is unimportant.