Wittgenstein died in 1951 (a year after I was born) at age 62. This was 30 years after publishing the Tractatusand two years before the Investigations was published. As everyone knows, he changed his views dramatically in the years following the publication of the Tractatus—perhaps the most dramatic self-repudiation in the history of philosophy. That work was pre-Socratic in tone: “all is logic” was its theme—and truth-functional logic at that. The book reads like the working out of an idee fixe, as if designed to be rejected, set up for failure; and very hard to understand. Ramsey challenged Wittgenstein with a more pragmatist philosophy, and pragmatism prevailed; the eventual result was the Investigations. Clearly Wittgenstein was not averse to changing his mind; he seems to have relished it. Very little of the earlier work survived this volte face: he speaks of that work as if written by someone else, someone utterly benighted. The question I want to ask is counterfactual: what if Wittgenstein had lived until he was in his eighties? What would he have made of later developments in philosophy? We have to guess, but our guesses can be informed. Some may believe that his views would have remained the same through the fifties and sixties, since he had arrived at the definitive truth (we might call these people “Wittgensteinians”). I don’t think so: I think he would have changed with the times, as he had before. The Investigations is notably backwards-looking, concerned with Wittgenstein’s early influences—Frege and Russell, in particular. Not much was going on in philosophy of language between the time of TLP and PI (Carnap doesn’t seem to have made much of a mark on Wittgenstein); things started picking up in the late fifties and sixties—too late for Wittgenstein to know about. I think he would have liked what he saw for the most part: Strawson, Grice, Davidson, Searle, Putnam, and others. I doubt he would have taken to Quine—too scientistic, too logic-obsessed. I’m not sure what he would have made of Kripke and Lewis, or Montague and Kaplan. The reason he would be receptive to such developments is that they fall between TLP and PI: they take logic seriously but they also respect the forms of natural language. Davidson’s use of Tarski’s theory of truth would particularly strike a chord: that approach precisely combines formal logic and actual speech (isn’t Wittgenstein the father of radical translation as a philosophical method?). They are also radically anti-empiricist in their assumptions: there is no talk of sense-data and the like, and no obsession with skepticism (unlike Russell). But I suspect Chomsky would have the biggest impact on Wittgenstein: he would have loved Chomsky. Why? Because Chomsky introduced formal linguistics and he connected the study of language to the functioning of the human mind—surface structure and deep structure, transformational grammar, competence and performance, biological naturalism and unconscious computation, innateness and modularity. It’s science without scientism, rigor without rigidity, description without desiccation. You might retort: “But Chomsky’s doctrines are completely antithetical to Wittgenstein’s!” That might well be true, but the whole point is that Wittgenstein was able to change his mind; and I think he would have. He would have seen the merits of the new approaches and accepted them, as he already had twice in his life (the first time in adopting the new logic under the influence of Frege and Russell). He wouldn’t have clung dogmatically to the old ways (as some “Wittgensteinians” do). It was his own work that partially led to the new ideas, both his early and later work, and he would have been well aware of that. He would appreciate the synthesis. He would also admire the novelty (who could not see that Grice was onto something?). Russell, for his part, would remain stuck in the mud, great man though he was, because of his life-long commitment to empiricism and his fear of skepticism. But Wittgenstein was not afraid of skepticism and saw through empiricism (he wasn’t a big Hume enthusiast—not that Hume was as empiricist as he was commonly supposed to be). Wittgenstein would have the same response as other philosophers of the period: this was good stuff, a step forward. I think he would view PI as too behaviorist in the light of the new philosophy of mind, and he wouldn’t be anxious to banish everything in TLP (it wasn’t totally wrong!). So, if he managed to produce a third book (Cognitive Grammar: An Exploration), it would also represent a change of position, a new beginning. That would be a very interesting book, produced at the height of his powers. The “Wittgensteinians” would be non-plussed.
 Model-theoretic semantics might well have struck him as a shade too close to the crystalline formalism of the Tractatus; and those worlds Wittgenstein invokes are suspiciously redolent of possible worlds in modal model theory. Lewis would surely raise the specter of metaphysics run amok. Tarski, by contrast, keeps it real (sequences, satisfaction, Convention T).
 In my opinion PI was a timely response to contemporaneous philosophy, especially philosophy of language. But by the late Sixties philosophy had moved on and that book was no longer very relevant to current discussions. I think that Wittgenstein would be well aware of this had he lived longer and would have modified his position accordingly. However, this is not the view of die-hard “Wittgensteinians” who want their hero to have anticipated and refuted the philosophical future. In the same way, Russell’s philosophy of language looks quaint today, however revolutionary it may have seemed at the time (that sparkling new logic!). It’s an interesting question what the Wittgenstein of the Tractatus would have made of the Investigations had he read it: he might well have viewed it as thoroughly retrograde, logically illiterate, and metaphysically timid. All that pointless description! So much slavish adherence to the appearances!