In its original version, before Wittgenstein decided to extend the book’s scope, the Tractatus advanced a solipsism of a decidedly etiolated sort – so etiolated, indeed, that the self which according to this solipsism claims ownership of the world ends up stripped of any substantial content. By the time it was published, however, the solipsism passage had been revised so as to gesture towards a puzzling ‘metaphysical’ subject, whose importance seems to be primarily (though no doubt not exclusively) ethical. By the time he wrote the Blue Book Wittgenstein no longer held the unitary conception of language on which his Tractarian conception of solipsism depended, but he continued to deny coherence of a substantial self.

In this chapter, I interpret section 6.361 of Wittgenstein’s Tractatus – containing Wittgenstein’s second reference to Heinrich Hertz in the book – in the context of the nearby framing remarks concerning the ‘law of causality’. Attention to the relevant details of Hertz’s work sheds light on a number of Wittgenstein’s remarks about mechanics in the 6.3s and, in particular, explains Wittgenstein’s claim that ‘What can be described can happen too, and what the law of causality is meant to exclude cannot even be described’ (6.362). For Wittgenstein, to describe events in causal terms is to describe them via an appeal to temporal and spatial asymmetries. However, no alternative is available: a description that did not appeal to such asymmetries would not be a description of anything. According to the Tractatus, descriptions are recognized as causal when they are embedded in a unified theoretical framework, but causal powers, understood as relations of material necessity, do not exist.