Contemporary philosophy comes in so many categories and types that even listing them can be dizzying. Race, gender, cultures, environmental, historical, disciplines, even style and humor are in the mix. Diversity and specialization ever lead, fueled by the tensions we explicate and the passions that compel us. Is this a halcyon period, a darker sign of fragmentation whose consequences we have begun to chart, some part of both, or cloth of another suit we have yet to wear? Time will tell.

Now turn back the epochal clock, just about a century ago. It’s 1919; a savage First World War has just ended with some 40 million or more dead. We know the story well enough. A shortsighted peace gains the victors their spoils, punishes the losers, redraws several continental maps while reinforcing colonialism, and sets the stage for a bloodier conflict to come about two decades later. The sequence, however clichéd, is worth mentioning. It certainly plays a part, for this reader at least, with the current book, which tracks four philosophers facing three questions, whose relevance sustains through it all: what can I know, how best use that knowledge, and how can I live?

The grand yet practical sweep of these questions keeps, Eilenberger, our author, focused on his task, and in a style infused by the discoveries made or proposed until he ends the book in 1929, as the NY stock market crashes. His eight chapters, thematically titled and chronologically arranged, sharpen the pace: prologue, leaps, languages, culture, you, freedom arcades, and time (with an attending epilogue). Brief internal vignettes refract the quartet -- Wittgenstein, Benjamin, Cassirer, and Heidegger – and the evolution of their thinking.

Attentiveness to person and relationships, from work to friendship, marriage and amatory; the character of the time, place, and culture in which the quartet wrote or taught; the struggles they endured to find an audience receptive to their views, and how they dealt with the audience they gained; and the arc of their rebellion against received Kantian paradigms inform the writing, which, with only several lapses, perhaps by way of the translation, is deft enough to admire. Equally so is a through-line that casts a critical eye on the influence of the university research institution -- rooted in strict disciplinary parameters and domesticated by bourgeois manners -- on philosophy. Of the quartet, only one, Benjamin, will fail to gain a professorial chair, despite his best efforts, and make his living as he can as an independent critic and commentator in periodicals and books.

With Wittgenstein’s decisive focus on language and its ambiguities, Cassirer’s auspicious embrace of structured symbolic forms, including and other than language, Heidegger’s insistence that Dasien and death mark us, the existential predicament we face individually and collectively, and Benjamin’s ingenious pivot to culture and its driver, mass market consumerism -- each defining perspectives for study -- it is something to consider how it worked out. The rejoinder is this: what can still inspire us to fully, clearly, and carefully analyze what we face and how we live in the coming, third decade of the 21st century? In the epilogue, Eilenberger leaves us with one final quote in this regard, and a subdued chuckle (considering who said it): “philosophy, what else?”