Philosophische Untersuchungen is, with the Tractatus Logico-Philosophicus, one of two major works by 20th-century philosopher Ludwig Wittgenstein. In it, he discusses numerous problems and u0026 puzzles in fields of semantics, logic, philosophy of mathematics and u0026 the philosophy of mind. He asserts that conceptual confusions surrounding language use are at the root of most philosophical problems, contradicting and u0026 discarding much the argument of the Tractatus Logico-Philosophicus. The book is often considered one of the most important works of the 20th century, continuing to influence contemporary philosophers studying mind and u0026 language. The book wasn't ready for publication when Wittgenstein died in 1951. G.E.M. Anscombe translated the ms and u0026 it was published in 1953. It's now in a 3rd edition incorporating Anscombe's final revisions and u0026 is repaginated. There are two popular editions of Philosophical Investigations:Prentice Hall, 1999 (ISBN 0024288101) Blackwell Publishers, 2001 (ISBN 0631231277) - bilingual. The text is divided into two parts, consisting of what Wittgenstein calls, in the preface, Bemerkungen, translated by Anscombe as and "remarks and ". In the 1st part, these remarks are rarely more than a paragraph long and u0026 are numbered sequentially. In the 2nd part, the remarks are longer and u0026 numbered using Roman numerals. In the index, remarks from the 1st part are referenced by their number rather than page; however, references from the 2nd part are cited by page number. The comparatively unusual nature of the 2nd part is due to the fact that it comprises notes Wittgenstein intended to reincorporate into the 1st. Due to his death, it was published as a 2nd part. Philosophical Investigations is unique in its approach to philosophy. A typical philosophical text presents a philosophical problem, summarizes and u0026 critiques various alternative approaches to solving it, presents its own approach, then argues in favor of that approach. This book treats philosophy as an activity, rather along the lines of Sokrates' maieutic method; he has the reader work thru various problems, participating actively in the investigation. Rather than presenting a philosophical problem and u0026 its solution, he engages in a dialog, where he provides a thought experiment (a hypothetical example or situation), describes how one might be inclined to think about it, then shows why that inclination suffers from conceptual confusion.