It is, of course, somewhat silly to review a classic work of philosophy, but after finishing "Philosophical Investigations," I felt compelled to write a few words about the experience.
I'd always heard that Philosophical Investigations was one of the most important works of philosophy of all time. Naturally, I thought that the task of reading it would be daunting, and in certain ways, it definitely is. However, I was also surprised at the strict dedication to clarity Wittgenstein displayed throughout this book. Wittgenstein's goal in this book is to undermine the tradition within Western philosophy which attempts to describe language as a set of innate, unchangeable categories. Earlier in his career, Wittgenstein was an enthusiastic participant in this tradition, but with Philosophical Investigations, he sought to call the entire project into question. More immediately, he's responding to his former mentor, Bertrand Russell. In a broader sense, he's challenging a tradition that started with Aristotle and continued through Descartes and Kant.
In one famous story about Wittgenstein's inspiration for pursing this project, Wittgenstein was conversing with the Italian economist Alfonse Sraffa. When Wittgenstein tried to explain the logical categories of language to Sraffa, Sraffa gave Wittgenstein the Italian chin flip, basically meaning "f-you," and asked Wittgenstein to explain the logical form of the gesture. I have no idea exactly how profound this encounter really was for Wittgenstein, but Philosophical Investigations is full of ruminations such as this one, which may seem innocuous on first glance, but have important implications for Western philosophy when thought through to their end. He subjects our assumptions about the logic of language to the ambiguous nature of the human mind and will through such thought-experiments.
Out of these experiments, he concludes that the nature of language usage is determined by context, and by implication, culture and history. Basically, his mentor Russell provided an understanding of language where language possessed an objective structure, which is then "filled-in" with historical and cultural experience. Wittgenstein attacks the notion that language is safe from the influence of culture and history. Our conception of what "red" is will ultimately be determined by what color-experience our vocabulary associates with red. Even our conception of what constitutes an object is determined in this way. A lever wouldn't be a "lever" to an individual who had no understanding of the way in which that object is supposed to be used as a lever. In one of the few instances where he quotes another philosopher, Wittgenstein refers to Frege's claim that a word is meaningless outside of a sentence. This may sound odd at first (I can yell "rain!" and it obviously means something), but Wittgenstein points out that at the end of the day, it's still pretty much true. Does a single word in a language you don't understand mean anything? Even if you knew the language, you would also have to have a thorough understanding of the way in which the word "rain" is supposed to be used, and to know how to distinguish between these usages.
Wittgenstein takes these various smaller observations and brings them to what is perhaps his most controversial position, which is that this contextualism applies to grammar itself. In turn, Wittgenstein argues that there can never be a "meta-language," a vocabulary which provides an objective understanding of what language itself is. Meaning will never truly be separated from grammar, even as we attempt to study grammar itself.
This is all, naturally, difficult subject matter. However, these subjects, in conjunction with Wittgenstein's exemplary use of the aphoristic style, makes for an enlivening reading experience. Nietzsche's influence on Wittgenstein is readily apparent- and not just in his philosophical positions. Philosophical Investigations is split into two parts: One part which primarily concerns itself with problems of language, and the other with problems of human consciousness. Both are made up of hundreds of aphorisms, few of which are longer than a paragraph. Although Philosophical Investigations is a well-crafted set of arguments, the aphorisms feel light-footed and easily quotable. The aphorisms, in their direct context, don't form a strict chain of thought. Rather, their relationship is more thematic, and the arguments arise out of their totality. In using this style, Wittgenstein seems as if he is walking along with the reader, showing them around the cityscape of our language and vocabulary. He is comfortable admitting when he himself feels confused about a certain point. Language is a thing which lives, and Wittgenstein, through his style, encourages the reader to "feel" its liveliness.
On a more practical note, this style allows Philosophical Investigations to be unusually clear for a major work of 20th century philosophy. Analytical philosophy prides itself on its ability to construct arguments which supposedly (and that's a big "supposedly") do not require cultural or historical reference to understand. Unfortunately, this can lead to its own sort of obscurantism, where the only vocabularies allowed expression are highly convoluted and technical in order to make up for its self-imposed limitations. Philosophical Investigations avoids this by refraining from stylistic absolutism, and as a result, Wittgenstein's thoughts float freely, held together by their natural momentum.
This is one of the few works of 20th-century philosophy that I would recommend beyond a philosophy-reading audience. Philosophical Investigations has inspired historians, anthropologists, fiction writers, sociologists, and all manner of people who are concerned with the nature of language. Really, despite its difficult subject matter, intellectual curiosity is the only thing you need in order to gain from reading Wittgenstein. In fact, having a literary disposition may help with reading it!