If we leave aside a few mavericks, such as Henri Bergson, John Dewey, George Santayana and A. N. Whitehead, the great bulk of modern Western philosophy falls into just a couple of categories. On the one hand we have the subjectivist schools related to existentialism, on the other, the various brands of "logical positivism," including linguistic philosophy. The former trend has, in general, had more of an echo in the Latin countries, especially France. The latter, until quite recently, enjoyed widespread support in the Anglo-Saxon world. We shall devote most of our attention to it, because of its pretension to represent the philosophy of science. The trend which dominated philosophy in Britain and the United States for the greater part of the 20th century, has appeared in different disguises, and under all kinds of aliases—neo-positivism, logical empiricism, empirio-criticism, analytical philosophy, etc., etc. Although it rose to prominence in Britain and the USA, it owes a great deal to German and especially Austrian philosophers. About the turn of the century, the physicist Ernst Mach was developing his philosophy of empirio-criticism. Mach, argued that it was impossible to prove the existence of the material world.
To most people, this idea may seem, to put it mildly, a bit peculiar. And so it is. Yet it has enjoyed considerable popularity with philosophers for most of this century. It is not, however, a new idea. It is based on the ideas worked out by Bishop Berkeley in the 18th century. This was the worst kind of subjective idealism, and the neo-positivists are not very pleased to be reminded of the real author of their philosophy. They regard themselves as scientific empiricists. But then, Bishop Berkeley’s ideas were ultimately derived from the narrow British philosophy of empiricism, based on Locke’s idea that all human knowledge comes from our senses.
Since all knowledge is derived from sense-perception, he argued, can I assert, for example, that this apple exists? Not at all. All I can say for certain is that I see it, smell it, taste it, etc. In other words, all that I can know is my sense-impressions. Despite all claims to the contrary, the inevitable conclusion of this line of thought is that only I exist. This view is known in philosophy as solipsism (from the Latin solo ipsus—"I alone").The argument that it is impossible to prove the existence of the physical world was answered by Engels as long ago as 1892, when he wrote, in the Introduction to the English edition of Socialism Utopian and Scientific:
"Again, our agnostic admits that all our knowledge is based upon the information imparted to us by our senses. But, he adds, how do we know that our senses give us correct representations of the objects we perceive through them? And he proceeds to inform us that, whenever he speaks of objects or their qualities, he does in reality not mean these objects and qualities, of which he cannot know anything for certain, but merely the impressions which they have produced on his senses. Now, this line of reasoning seems undoubtedly hard to beat by mere argumentation. But before there was argumentation there was action. In Anfang war die Tat (‘In the beginning was the deed,’ from Goethe’s Faust, Part I, Scene III.) And human action had solved the difficulty long before human ingenuity invented it. The proof of the pudding is in the eating. From the moment we turn to our own use of these objects, according to the qualities we perceive in them, we put to an infallible test the correctness or otherwise of our sense-perceptions. If these perceptions have been wrong, then our estimate of the use to which an object can be turned must also be wrong, and our attempt must fail. But if we succeed in accomplishing our aim, if we find that the object does agree with our idea of it, and does answer the purpose we intended it for, then that is positive proof that our perceptions of it and of its qualities, so far, agree with reality outside ourselves." (MESW, Vol. 3, p. 101.)