Metaphysics is concerned with the ultimate nature of reality - which throughout human history was regarded as the single most important intellectual subject. Yet from the middle 19th century, it incrementally became the consensus among philosophers that metaphysics was meaningless, nonsense or actively harmful - and almost all philosophers worked at a more superficial level of 'analysis' in fields such as epistemology (concerning the possibility of knowledge, or logic, or ethics or whatever.
These philosophers assumed that they had dispensed with metaphysics, but of course they had not; they simply became unaware of (or denied) their own assumptions concerning the nature of reality; and in almost all cases this included the assumption that there was no god, reality was not 'created' nor sustained by a god, and certainly that reality was not created for Man and for individual men and women.
What were the criticisms of the philosophical activity of metaphysics that led to its rejection? These are some:
1. That it is purely subjective - everybody has their own individual and idiosyncratic ideas (unless some individual or groups succeeds in imposing their metaphysics on many other people).
2. That metaphysical statements are imprecise - so imprecise as to be useless, meaningless, platitudinous, non-contributory. This would include ideas such as 'god', 'creation', Man, Good and so on.
3. That metaphysics had a covert agenda (of some kind of religious, reactionary, oppressive type) - an agenda which could be avoided by avoiding metaphysics.
4 That there is no evidence for (or against) metaphysical statements. Thus they are meaningless, nonsensical, or not-what-they-seem.
The recommendations from such analysis were that people should stop using metaphysical language; should stop talking-about, discussing, or arguing-about metaphysics. The safest thing was to remain silent on the topic; but when people refused to keep quiet on the subject, they should be ridiculed as stupid, crazy or confused (or covertly malign).
(This implicitly applied to nearly all of philosophy before the early 1900s; unless it could - like selective readings of Aristotle, Locke, Hume, Kant etc, be seen as the first baby-steps towards a state of non-metaphysics.)
1. That metaphysics is subjectively inflected, includes subjectivity, does not imply that it is purely subjective.
2. That metaphysical statements are imprecise does not imply that they are therefore utterly useless as communications. That communications are unreliable does not imply that nothing is being communicated-about.
3. That metaphysicians have a covert agenda does not imply that that a covert agenda can be (or has been) avoided by avoiding mention of metaphysics.
4. That metaphysical statements cannot be verified or refuted by empirical, observational, experimental, experiential evidence is, in the first place: not distinctive to metaphysical statements (it applies to all statements since there are no non-arbitrary rules to generate truth from empirical data); and secondly untrue in the sense that metaphysical statements can be tested from consistency (the demand for consistency being and implicit but denied metaphysical assumption of many self-styled opponents of metaphysics; and thirdly, subtracting metaphysics makes many observable differences to human life (or else the advocates of ignoring metaphysics would not bother advocating) - thus particular metaphysics does not lack distal empirical consequences.
We must ask why insist on silence about metaphysics? Why introduce this ethical imperative? On what grounds?
The usual answer is to say that the new (post-empirical) philosophy is about achieving clarity... but why is clarity supposed to be a good or desirable thing? In the first place there is zero evidence that clarity is helpful (philosophers don't have observably better, happier or less-suffering lives than a controlled comparison group of non-philosophers; nobody even tries to suggest that they do).
And clarity is very obviously not important in leading a good life - honest philosophers will usually admit that a comforting delusion is a better basis for happiness than (supposed) clarity.
And who says that modern philosophers are clear? Nobody else finds them at all clear! Indeed, they are a by-word for un-clarity, and modern philosophical work is avoided by everybody who does not have a professional reason to engage with it! (Non-philosophers usually find pre-moderns to be much clearer, and more helpful in living.)
If we are to exclude and forbid metaphysics, why on earth stop there? All the strictures brought against metaphysics apply far more widely - probably to all language, all communications, all statements about the world... The terminus of anti-metaphysics is indeed nihilism: the denial of any real-reality (or any which can be understood or spoken of); and nihilism leads to despair.
In sum; the rejection of metaphysics - which has affected essentially all modern professional philosophy - is dishonest (being prejudicially but arbitrarily applied only to metaphysics, but not to favoured forms of knowledge); incompetent (being grossly over-inclusive in its criticisms, but failing to see this); and clearly (therefore) driven by a hidden agenda (or else why would all acknowledged professional philosophers have followed the 'party line' so slavishly).
That hidden agenda, driving anti-metaphysics, is precisely the destruction of all values (i.e. nihilism).
As an alternative I suggest the following:
If we accept that an individual may have knowledge (and if we don't accept this we must stop at that point, because discussion really is futile!) then - given the intrinsic uncertainties of communication - there must be a direct way of knowing that does not involve communication.
In other words, at least some individuals must, in principle, be able to apprehend reality directly (even if this apprehension is regarded as susceptible to partiality and distortion, due to the finite nature of individuals).
Direct knowing must include metaphysics, or else all other forms of knowledge are intrinsically undermined.
(If metaphysics is possible and defined as the most fundamental form of knowledge, then all more superficial forms of knowledge rely upon it - and wrong or absent metaphysics will undermine all other forms of knowledge.)
This leaves open the specific nature of metaphysics. People must be able to know it, but need not be able to communicate it - precisely because they can know it directly.