Peter Hacker does not abide nonsense. In his January article "Why Philosophy" Hacker puts in his cross-hairs ideas taken seriously by politicians, scientists, and the intelligentsia in general. Let’s get to the specifics in a minute – the general outline is relevant to anyone hoping to grok the never-ending attempt to define philosophy. Perhaps this attempt never ends because there’s no exhaustive definition available, or perhaps the activity is perpetual because of distinct approaches and traditions even within the “Eurocentric” philosophical tradition (see Rian Mitch's post on the Analytic/Continental Divide).
The preoccupation with defining philosophy does not only manifest itself in introductory contexts; it's a scholarly endeavor as well (see here, here, and here). No matter which tradition we hail from, the “meta” nature of philosophy seems to inevitably lead us back to deciding what it is we’re up to when doing the thing we've been doing all along. Hacker’s contribution to the discipline’s introspection is very much a part of the academic niche he fills, namely as an inheritor of the philosophy (or, as some would call it, the anti-philosophy) of Ludwig Wittgenstein.
To get to those aforementioned specifics, Hacker attacks the idea so prevalent in the cognitive sciences today that the mind is nothing but the brain. Hackers assures us that showing how confused the notion is would take more time and space than his article allows, but in the face of claims of mind-brain identity from scientists, Hacker advises us not declare “how interesting!,” but to skeptically ask “does my brain have political opinions,” “does it speak English,” etc. Hacker believes that the brain, even if it’s necessary, is not sufficient for possessing things like political opinions or a spoken language.
If philosophy is, as it's commonly claimed, about providing conceptual clarity, precision, and coherence where it would otherwise be lacking, then a philosopher might celebrate Hacker for rounding up invading forces from science, but he also dismisses as “foolishness” many of the philosophical views settled upon in an attempt to answer the questions philosophers have traditionally grappled with – examples including the unreality of time and the proposition that we cannot know the thoughts of another, which Hacker calls paradoxical, and absurd. But it’s not only out-of-vogue philosophical views Hacker attacks; the postulate of “necessary truths,” illustrated by the formulation “water=H2O in all possible universes” also receives no quarter, the view that helped revitalize the long dormant meta-physical doctrine of Essentialism in contemporary philosophy – this was no small development.
Hacker’s impatience with so much of academic philosophy is consistent with his role as an heir of Wittgenstein. Wittgenstein set about to unwind what he thought were conceptual confusions in the history of philosophy, confusions which lead to philosophical “mysteries” (which in turn lead to the many proposed ways of dealing with the supposed mysteries). He proposed in its stead a kind of therapy, in which those engaged in philosophical reflection can see the error of their ways (i.e. that the traditional questions of philosophy are not answerable on their own terms, and only seem legitimate because of deep conceptual confusions).
The therapy offered by Wittgenstein and Hacker is not one of positive affirmation. To pursue Hacker’s metaphor further, this therapy turns into downright law enforcement, as philosophy's role is in acting as a kind of border patrol. Philosophy patrols the borders between sense and nonsense, says Hacker, and he tells us that philosophy’s special role is in detecting this nonsense, assuring that with philosophy on the lookout, we can be safe from nonsense advanced not only by physical scientists, but by economists, churchmen, and ideologues in general. Reading from Hacker’s own charges, however, we can see that philosophy is guilty of nonsense as well, which was arguably Wittgenstein’s central and most important thesis.
So Hacker gives a common defense of the role of philosophy, namely that it provides clarity, precision, and coherence where it’s sorely needed. But the irony is that philosophy itself, in an article promoting the discipline, doesn't evade the long arm of the law. Indeed we can imagine many philosophers rounded up by Hacker’s border patrol. And in witnessing this hypothetical event, we have to wonder what it is that makes these philosophers characteristically “philosophical.” It’s likely that Hacker’s defense of philosophy will turn too many philosophers into outlaws who've run afoul of the discipline, rather than the standard bearers we imagine many of them to be. And so the attempt to find a satisfactory definition of philosophy continues, in perpetuity. Wittgenstein would likely have been annoyed at all this fascination with definition. Notice Hacker chose not to title his article “What is Philosophy?”