The positivists declared metaphysical sentences meaningless. This required them to be able to identify a metaphysical sentence. But how could they do that if such sentences literally have no meaning? It could not be by recognizing them as meaningless, though that is certainly an intelligible mental act, because many sentences are meaningless without being metaphysical—not all gibberish is metaphysical gibberish. Being gibberish is not sufficient for being metaphysical, though it may be necessary (according to the positivists). The answer, of course, is that metaphysical sentences are perfectly meaningful and are recognizable as metaphysical by being meaningful: we can see that they are both meaningful and not empirically verifiable. But the positivists are not permitted to say that by their own doctrine, so their position is self-refuting. It would be different if such sentences had a different kind of meaning altogether, as ethical sentences are alleged to; then the positivist could claim them to be meaningless only as construed as fact-stating (assertoric, cognitive). But that is highly implausible—they aren’t merely expressive or imperative. They are straightforward indicative sentences. So, there is really no alternative to the commonsense view that metaphysical sentences are meaningful, though not empirically verifiable (we can all agree that they are not mere tautologies). The simple truth is that the positivists could pick them out as metaphysical only by knowing what they mean, which is surely what they did; but then they can’t turn around and declare them meaningless. How could a meaningless sentence count as metaphysical in meaning?
 You might question whether there is any point in flogging the dead mackerel of positivism, since it perished decades ago, but actually the ghost of positivism still lingers, ready to leap from the shadows. It is therefore worthwhile to point out its flaws (many scientists still believe it, if only implicitly).