Pluralism and the possibility of philosophy
In a sense one might regard the transition from monism to pluralism, as exemplified in the contrast between Tractatus and Philosophical Investigations, as a move that rescues the possibility of philosophy. In the monistic (absolutistic) approach of the Tractatus (but that applies to many others; cf., e.g., Being and Time) philosophy is doomed by the ineffability of any kind of analysis that leads to non-contingent answers. In a pluralistic setting, such as the one explored in Philosophical Investigations, On Certainty, however, there is at least the possibility of reflection from within one framework on another framework. (But additional conditions have to be met, of course.) Interestingly, the result of such a reflection is not descriptive, but conceptual. And to the extent that it is possible, one might regard it as a kind of reflective investigation of imagination.