Editing Philosophical Investigations (section)

== Relation to Wittgenstein's body of work ==

In its preface, Wittgenstein says that ''Philosophical Investigations'' can "be seen in the right light only by contrast with and against the background of my older way of thinking". Wittgenstein biographer [[Ray Monk]] writes, "This is partly because of the great differences between his early and late work, but also because of the equally important continuities between the two".<ref>Monk, Ray (2005). ''How to Read Wittgenstein''. London: Granta Books, pp. 63-64.</ref> The early work in which Wittgenstein expressed his "older way of thinking" is the only book Wittgenstein published in his lifetime, the ''[[Tractatus Logico-Philosophicus]]''. 

The ''[[Blue and Brown Books]]'', a set of notes dictated to his class at Cambridge in 1933–1934, contain the seeds of Wittgenstein's later thoughts on language and are widely read as a turning point in his philosophy of language—"as an early prototype for subsequent presentations of Wittgenstein's later philosophy".<ref>Monk, Ray (1990). ''Ludwig Wittgenstein: The Duty of Genius'', New York: The Free Press, p. 337.</ref>

The American philosopher [[Norman Malcolm]] credits [[Piero Sraffa]] with breaking Wittgenstein's hold of the notion that a [[proposition]] must literally be a picture of reality by means of a rude gesture from Sraffa, followed by Sraffa asking, "What is the logical form of <em>that</em>?"<ref name="Malcolm">{{cite book |title=Ludwig Wittgenstein: A Memoir |edition=2nd |pages=57–58 |author=Norman Malcolm}} In the first edition, the incident is described on page 69. See also, [[Ray Monk|Monk, Ray]], ''Ludwig Wittgenstein: The Duty of Genius'', New York: The Free Press, 1990, pp. 260-261.</ref> In the Introduction to the book written in 1945, Wittgenstein said Sraffa "for many years unceasingly practiced on my thoughts. I am indebted to this stimulus for the most consequential ideas in this book".<ref>{{cite book |title=Philosophical Investigations |date=1958 |publisher=Basil Blackwell}}</ref>