The Tractatus opens with the famous declaration: “The world is everything that is the case” (TLP 1), followed by the qualification: “The world is the totality of facts (Tatsachen), not of things” (TLP 1.1). One is immediately struck by the dogmatic, absolutely authoritative tone of these claims. We do not at once know why they have been offered up, or what the basis for asserting them might be, nor will any later justifications be provided. They present themselves, in the words of the Preface, as “unassailable and definitive” (TLP p. 28) – beyond reproach it seems, but also, perhaps, beyond proof. What is the stance of the Tractatus? From what position are its absolute pronouncements. made?

One might suppose that such self-reflective questions would have little relevance to the opening of the Tractatus. The text at this point looks entirely outward, on to the world; any concern with the conditions of its own utterance apparently falls outside of its purview. It is as if the author of the Tractatus were completely absorbed into the external reality that is here described – as if Wittgenstein were, so to speak, presenting a realist's perspective purely realistically. If that is the case, however, we must recognize that this cannot itself be an unself-conscious move on his part. For at 5.634, after denying that there is an “a priori order of things,” he remarks: “Here it can be seen that solipsism, when its implications are followed out strictly, coincides with pure realism.