Philosophical Investigations summary

This shift in perspective about language’s true, unruly nature – refusing reduction to any fixed essence – has bigger implications than it might first appear. Consider the category represented by the word, “game.” Board games, Olympic competitions, children’s make-believe – they share almost no similarities, but they are called games. 

What essence unites this diversity spanning from something like poker to international soccer leagues? Wittgenstein's simple answer is that games, like many ideas, align through overlapping characteristics – interlacing, spiraling, redistributing meaning across webs of similarity open to constant flux based on one’s perspective. He terms these criss-crossing fibers of meaning, family resemblances.

From logical structure to fluid use, fixed essence to family resemblance, solved problems to perpetual questions – at each turn, language’s messy habitats thrive beyond the ability to define them. So Wittgenstein invites thinkers to dissolve stubborn language knots by attuning to ordinary use, as unassuming as one’s morning bread.

This is because he came to see that philosophical problems often arise from assuming words operate like gears of some abstract machine. This is based on the idea that language is a self-contained system that perfectly corresponds to reality according to a set of logical rules. But in reality, people usually just muddle through, using words in ways that depend on versatile context more than strict consistency.

Wittgenstein’s seismic shifts in thought are still rippling outward in philosophy today, and his rediscovery of language’s dynamics nurtured more modern trends. His legacy is explicitly crystallized in what came to be known as the school of ordinary language philosophy which thrived after his death. For example, British philosophers J.L. Austin and Gilbert Ryle avoided theorizing an ideal language by meticulously observing everyday speech. Their examinations of mundane chatter and psychological verbs proved sensationally groundbreaking. Likewise, the Vienna Circle positivists, a group of philosophers, scientists, and mathematicians who met regularly from 1924 to 1936, pressed philosophy to critique ideas on their practical, empirical merits rather than theoretical abstractions alone.

But most profoundly, Wittgenstein foreshadowed seismic shifts still rocking the humanities today. Half a century before postmodernism, he flagged truth's reliance on local language games rather than some absolute fixed meaning. In doing so he anticipated postmodern and poststructuralist views of knowledge as socio-historically situated constructions, perpetually made and remade anew.

Though Wittgenstein’s conceptual shifts in philosophy remade contemporary thought, his own life continued with an unrelenting inner turmoil. While his life after Tractatus saw him escaping to a simple, rural life, his last decade saw him once again rooted in academia at Cambridge University. There he mostly dispensed with formal lectures, preferring instead to provoke spontaneous Socratic dialogues with students, probing the endless puzzles of language and mind.

However, the students often left these lectures incredibly confused. Only a few, sharp souls and keen minds, like Elizabeth Anscombe, were able to grasp the extraordinary visions Wittgenstein wrestled with alone at his desk. There, late evenings found him scribbling endless pages with chewed pencils, filled with remarks and arguments with himself in multiple voices. Gradually these fragmented digressions coalesced into the intricate musings that became the Philosophical Investigations.