[blancNoir]

I'd also suggest Wittgenstein's Tractatus Logico-Philosophicus, a seminal work of the logical positivist movement. Influenced by Frege's predicate calculus, the aim of the Tractatus was to determine an isomorphic relationship between language, thought, and external states of affairs. An axiomatic attempt to reveal a potentially ideal logical language, that is not interested in meaning per se, but merely an accurate reflection of the world. A closed system that essentially excludes non-falsifiable metaphysical question. Famously concluding with the instruction: "Whereof one cannot speak, thereof one must be silent." Part of Wittgenstein's project, even in its early aggressively logical form, was philosophy as a therapeutic. That is, the metaphysical questions concerning god, being, essence, and forms that had inspired thousands of years worth of fevered conversation, could be finally be quieted. That's not to say they couldn't be meditated on, but were not in the domain of his logical language, and so silence. Again, I think early Wittgenstein sometimes gets misinterpreted, "...therefore one cannot speak" does not, to me, mean that it can't be considered or one must forgo spirituality, just that it couldn't be spoken of within the project of the Tractatus.

Logical empiricism was ultimately a dead end as the criteria for even verifying empirical truth has long been contentious philosophically, and was further critiqued by contemporaries such as Quine who attacked the premise of the analytic/synthetic distinction (think Hume's fork, which Kant tried to solve) and Popper who cited the problem of induction to critique the fundamental premises of the positivists verificationism.

Wittgenstein is an interesting case, as the Tractatus is considered an early work of his, profoundly influential to analytic philosphy at the time, yet his later work, Philosophical Investigations is sometimes seen to retract the dogmatism found in the Tractatus. I tend to take the view that it's a continuation of his thought, rather than a retraction of his earlier work. Crudely, whereas his former thought represented a narrowly axiomatic definition of language and its truth value, PI investigates, among many other ideas, language as an activity, or game, that has meaning dependent on the context of its use, languages as families. Granted, Wittgenstein is a complex thinker and these are simply my interpretations.

It's also curious to note that as positivism was beginning to fall out of favor around the time of the second world war, a continental thinker such as Heidegger, whose thought luxuriated in the kind of metaphysical questions the positivists necessarily eschewed, rose to prominence and was infamously sanctioned by the NSDAP to philosophize about their presumed "destiny". Bit of a tangent, but I think the historical context is relevant, as often philosophical movements are birthed from pre- and post-war attitudes.