This approach caused something of a revolution in analytic philosophy, and spawned a movement known as "ordinary language philosophy" that came to prominence at Oxford in the decades following the Second World War. The debate between ordinary language philosophy and traditional philosophical methods has been rife with misunderstanding, largely because Wittgenstein's thought does not simply adopt a position contrary to tradition, but also introduces new methods and new approaches that have not been assimilated by the tradition.
One way of understanding Wittgenstein's new approach is to say that there is no special body of knowledge that belongs to philosophy. Physics, for instance, has its own field of investigation and its own special terminology—words like "mass," "energy," "electron," and so on. We might think analogously that philosophy can also investigate concepts such as knowledge, selfhood, and language, and adopt its own special terminology to deal with these theoretical issues. But unlike physics, philosophy employs a double standard. On one hand, in inquiring into the nature of knowledge, we treat "knowledge" like a technical term that refers to something whose nature is as yet unclear and that we must uncover. But on the other hand, this investigation draws on the word "knowledge" as we use it in everyday speech. A physicist who researches what an a electron is investigates something as yet undiscovered; in investigating what knowledge is, we are puzzling over a word with which we are already familiar.
We all know perfectly well how to use "knowledge" in ordinary contexts. But when we extract "knowledge" from these ordinary contexts and simply ask, "what is knowledge?" we are at a loss how to respond. Metaphysical speculation, according to Wittgenstein, arises when we take such words out of their ordinary contexts and ask about the nature of the thing itself. Wittgenstein points out that "knowledge" is a word, and words mean what they do by virtue of being used in the contexts that they are used. If we remove "knowledge" from all contexts and ask what the thing itself is we are at a loss precisely because, outside of all contexts, the word cannot mean anything at all.
Wittgenstein's method can be called "therapeutic." He is not making new discoveries or providing new explanations, but is employing a purely descriptive method to untie the knots in our thinking that are caused by metaphysical speculation. In section 127 he says, "The work of the philosopher consists in assembling reminders for a particular purpose." His method is to remind us of the various contexts in which words such as "knowledge" make sense, and to show that they have no meaning beyond what we find in those contexts. We end up not with an understanding of what knowledge is, but only with a reminder of what we have always known: we can form coherent sentences that include the word "knowledge."
If Wittgenstein's philosophy is a therapeutic untying of mental knots, his methods are as diverse as the various temptations that lead us into metaphysical thinking. He uses language-games, discusses rule following, and investigates supposed mental states and mechanisms. Most of his methods are entirely new because his project is entirely new. He is going in the opposite direction of traditional philosophy, and trying to lead us away from complex theories rather than into them. While this section of the text outlines the direction of his thought, we are best able to understand it by delving into the various "therapies" he applies in the rest of the text.