Reading it now, you can see why it was explosive, with its combination of wit and flagrant disavowal of interpretive charity. Gellner is happy to attribute bad motives, bad ideas and sheer confusions to the philosophers he dislikes, and he is often very funny in doing so.
Academic environments are generally characterised by the presence of people who claim to understand more than in fact they do. Linguistic Philosophy has produced a great revolution, generating people who claim not to understand what in fact they do. Some achieve great virtuosity at it. Any beginner in philosophy can manage not to understand, say, Hegel, but I have heard people who were so advanced that they knew how not to understand writers of such limpid clarity as Bertrand Russell or A. J. Ayer.
It is not clear whether Moore should be called a philosopher or a pedant of such outstanding ability as to push pedantry and literal-mindedness to a point where it became a philosophy. [...] One might say that Moore is the one and only known example of Wittgensteinian man: unpuzzled by the world or science, puzzled only by the oddity of the sayings of philosophers, and sensibly reacting to that alleged oddity by very carefully, painstakingly and interminably examining their use of words...There are many more passages like this; although it is quite repetitive, I recommend reading the whole book.
It is a shame, however, about the preface to the new edition by Ian Jarvie, which is a missed opportunity. What Gellner mainly objects to in the "ordinary language" approach is its attack on philosophical doctrines as meaningless, its argument that philosophical problems always arise from linguistic confusion, and its consequent resistance to constructive theory: philosophy is therapy. Jarvie insists that "Linguistic Philosophy continues to be the tacit backbone of 'analytic philosophy', uncritically unacknowledged." This is simply false. Most of the strategies and arguments that Gellner rejects are dormant nowadays. Constructive theory is rife. The only general continuity lies in paying attention to language, but Gellner is rightly tolerant of that: it is a problem for him only when it becomes exclusive. A good essay could have been written, in the spirit of the book itself, about the recent history of philosophy, and the complicated place of Austin and Wittgenstein within it.
In any case, the value of Words and Things is not mainly in the light it casts on contemporary practice, or in its critical arguments – for Gellner, "exposition and refutation are one", and subtle distinctions are not worth bothering about – but in its sociological attitude to philosophical thought. This is easy to caricature. It can be reminiscent of an article once published in the The Sun, about a psychiatrist who diagnosed Wittgenstein as schizophrenic, observing that his work is "superficially profound, but on examination, meaningless." In Gellner, it occasionally amounts to pseudo-science: "[a] rough law holds for the history of philosophy, namely: P = 1/p, where P is Platonism and p psychologism." It has to be legitimate, however, to ask about the motives of philosophers. Some of the best insights in Gellner's book are of this kind, as when he explains the appeal of the later Wittgenstein:
The linguistic naturalism, the reduction of the basis of our thought to linguistic etiquette, ensures that there is no appeal whatever to Extraneous Authority for the manner in which we speak and think. Naturalism, this-worldliness, is thus pushed to its final limit. But at the very same time, and for that very reason (language and custom being their own masters, beholden and accountable to no Outside norm), the diversified content of language and custom is indiscriminately endorsed. Thus the transcendent, if and when required, slips back ambiguously, in virtue of being the object of natural practices, customs, modes of speech.
Apart from its sarcasm, this seems to me an apt account of the attractions of anti-foundationalism, in one of its forms. It is akin to the "naturalism of second nature" in John McDowell's Mind and World: we hope to integrate irreducible normativity into the natural world by giving a naturalistic account of how we come to think about irreducible norms. You can see why someone would want this to work.
I don't mean to be disparaging. In fact, I find it striking that my own philosophical views, with one or two exceptions – atheism, for instance – are ones that I want to be true. Does that apply to other philosophers? How often do we argue against our heart's desire? And would it undermine philosophy to learn that it is, like metaphysics in Bradley's definition, "the finding of bad reasons for what we believe upon instinct"?