Bertrand Russell, answered from the texts and cited to the page.
Logical atomism is the view that the world can be analyzed, at least in theory, into ultimate simple constituents — particulars, qualities, and relations of various orders — and that these simples possess a kind of reality that belongs to nothing else.1 The method begins with what is apparently complex. Tables, chairs, Socrates, Piccadilly — everything to which we habitually give a proper name presents itself as a complex entity, some kind of unity that invites a single appellation.2
The task is to ask whether that apparent unity is genuine or whether it dissolves under analysis into something more fundamental. My answer is that it almost always dissolves. What we call things — persistent objects occupying space and enduring through time — are better understood as logical constructions or symbolic fictions, classes of particulars collected together for convenience rather than genuine single entities.3
The particulars themselves are not to be conceived on the analogy of bricks in a building; the better image is notes in a symphony, each lasting only a very short time, the "thing" being no more real or substantial than the rôle of the trombone.4 Numbers illustrate the point well. If you suppose that 1, 2, 3, and 4 are genuine entities inhabiting some realm of being, you immediately generate a large metaphysical apparatus and a particular analysis of arithmetical propositions — when you say that 2 and 2 are 4, you suppose the numbers to be constituents of the proposition.
But numbers are classes of classes, and classes are logical fictions, so numbers are fictions at two removes; they are not among the ultimate constituents of the world.5 The epistemological foundation of the whole structure rests on sense-data — those particular patches of colour, particular noises, and so forth that are singled out by attention.6
Sense gives acquaintance with particulars in a two-term relation: the object can be named but not asserted, and the relation is inherently incapable of truth or falsehood.7 Physical objects, by contrast, are not directly known; they must be exhibited as functions of sense-data if physics is to be verifiable at all.8 The program of logical atomism is in large part the attempt to carry out that exhibition.
The other sort of object one encounters — facts — is of a quite different character. Facts are what propositions assert or deny; they are not entities in the same sense as their constituents, and the proof of this is that you cannot name them.9 You can assert, deny, or consider a fact, but naming requires an object that is simply there, and facts are not there in that way.
One purpose running through all of this is the justification of analysis itself — the claim that you can get down, in theory if not always in practice, to simples out of which the world is built.10 And a secondary benefit, which I regard as considerable, is the dissolution of the traditional problems of metaphysics. Almost all of those problems, I am convinced, arise from failures in what might be called philosophical grammar — from treating grammatical form as a reliable guide to logical form, which it is not.11
One purpose that has run through all that I have said, has been the justification of analysis, i.e. the justification of logical atomism, of the view that you can get down in theory, if not in practice, to ultimate simples, out of which the world is built, and that those simples have a kind of reality not belonging to anything else.Part II, pp. 280–281
All the kinds of things to which we habitually give proper names are on the face of them complex entities: Socrates, Piccadilly, Rumania, Twelfth Night or anything you like to think of, to which you give a proper name, they are all apparently complex entities.Part II, pp. 215–216
Classes or series of particulars, collected together on account of some property which makes it convenient to be able to speak of them as wholes, are what I call logical constructions or symbolic fictions.The Collected Papers Vol 8, The Philosophy of Logical Atomism 1914-19, pp. 123–124
The particulars are to be conceived, not on the analogy of bricks in a building, but rather on the analogy of notes in a symphony. The ultimate constituents of a symphony (apart from relations) are the notes, each of which lasts only for a very short time.The Collected Papers Vol 8, The Philosophy of Logical Atomism 1914-19, pp. 123–124
Numbers are classes of classes, and classes are logical fictions, so that numbers are, as it were, fictions at two removes, fictions of fictions. Therefore you do not have, as part of the ultimate constituents of your world, these queer entities that you are inclined to call numbers.Part II, pp. 280–281
When I speak of a 'sense-datum', I do not mean the whole of what is given in sense at one time. I mean rather such a part of the whole as might be singled out by attention: particular patches of colour, particular noises, and so on.The Collected Papers Vol 8, The Philosophy of Logical Atomism 1914-19, p. 52
sense gives acquaintance with particulars, and is thus a two-term relation in which the object can be named but not asserted, and is inherently incapable of truth or falsehood.The Collected Papers Vol 8, The Philosophy of Logical Atomism 1914-19, p. 52
Physics exhibits sense-data as functions of physical objects, but verification is only possible if physical objects can be exhibited as functions of sense-data.The Collected Papers Vol 8, The Philosophy of Logical Atomism 1914-19, p. 52
facts are the sort of things that are asserted or denied by propositions, and are not properly entities at all in the same sense in which their constituents are. That is shown in the fact that you cannot name them.Part II, pp. 280–281
One purpose that has run through all that I have said, has been the justification of analysis, i.e. the justification of logical atomism, of the view that you can get down in theory, if not in practice, to ultimate simples, out of which the world is built.Part II, pp. 280–281
I think that practically all traditional metaphysics is filled with mistakes due to bad grammar, and that almost all the traditional problems of metaphysics and traditional results—supposed results—of metaphysics are due to a failure to make the kind of distinctions in what we may call philosophical grammar.Part II, pp. 280–281