Metaphysics is commonly criticized on the grounds that those who practice it rely on unfounded common-sense intuitions about the world. Such criticisms are methodological, because they contend that the methods on which metaphysicians rely are untrustworthy.
Another kind of criticism holds that metaphysical inquiry just isn't worth it. Simply put, why bother with questions about the nature of causation, of properties, of free will, and so on? Life is short, and there are many more pressing worries to attend to, e.g. [insert your favorite socio-political concern]. Call this a pragmatic criticism of metaphysics, since it argues that metaphysics isn't pragmatically worthwhile.
Bas van Fraassen (2002) advances one of the most interesting versions of the pragmatic criticism that I have come across in the literature. The idea is that, prior to engaging in any theoretical discipline, we ought to consider the potential costs and benefits of doing so. Take the case of science: if we are in the business of constructing scientific theories, we risk acquiring false beliefs about the world, if such theories turn out to be false. But all wouldn't be lost -- our false theory could still be very useful, in helping us to predict future events, improve our technology and thereby contribute to human well-being. Plenty of theories now considered strictly false are nevertheless incredibly 'useful' in the foregoing sense of the term. Hence, van Fraassen tells us that we shouldn't be put off by the risk of accepting false scientific theories, because the likely gain in practical benefits is well worth such a risk.
Now take the case of metaphysics. If I accept a metaphysical theory, e.g. about the nature of free will, and this theory turns out to be true, I've acquired a true metaphysical belief -- and that's it. None of the practical benefits that come with successful scientific theories likewise follow from true metaphysical ones. Depressingly, this means that if my metaphysical theory about free will turns out to be false, I acquire nothing at all! Nothing, that is, except for the nice feeling of having explained something. Considering that the risk of getting it wrong is pretty darn high (judging by the embarrassing amount of unresolved disagreement between metaphysicians), metaphysics, van Fraassen concludes, just isn't worth all the effort. James Ladyman (2011), though generally sympathetic to van Fraassen's position, qualifies it with the claim that some metaphysical theories have indirectly contributed to scientific progress. Highly successful scientific paradigms, like Newton's physics, were inspired by metaphysical views like atomism. This leads him to posit a criterion that any worthwhile metaphysics must meet: "the fertiliser of naturalised metaphysics has no value if it does not help the tree of science bear empirical fruit". This fits nicely with his advocacy of a thoroughly naturalised metaphysics, which concerns itself only with drawing connections between the different sciences. Of course, most metaphysical endeavours would be excluded by this criterion. Theories about the nature of free will or personal identity are unlikely to inspire successful scientific theories.
But, returning to van Fraassen, is it correct that false metaphysical theories can give us nothing at all, except a possible indirect contribution to the march of science? Unsurprisingly, I do not think so. Insofar as we care about the sorts of questions that metaphysics addresses, it isn't clear to me that having false answers to such questions is worse than having no answer at all. This is especially true if we understand the aim of metaphysics to be the construction of a coherent worldview. A worldview (from the German Weltanschaaung) is a system of beliefs about what the world is 'basically like', and how we fit in it. Worldviews typically include beliefs about whether there is a God or not, how the mind relates to the body, whether the world is as it appears to us, and so on. Clearly, having a worldview is something that many (most? all?) humans beings in fact want. If that is the case, then perhaps having a false worldview is better than having no worldview at all.
The question of what it is that makes the possession of a worldview desirable is one that I hope to address in more detail in subsequent posts. For now, I will content myself with some tentative suggestions:
1. Having a worldview is admirable, because it manifests the distinctly human ability to think beyond everyday concerns. To risk being accused of anthropocentrist elitism, I think there is something uniquely noble about creatures that strive to discover who they are and what their place in the world is. A world containing such creatures, everything else equal, is greater than one containing creatures who only ever think about what they will be eating tomorrow (if they can think at all).
2. Having a worldview gives us a perspective from which to interpret our lives and the world as we experience it. This is closely related to what R.M. Hare called a blik, roughly, a way of looking at things. My interpretation of a loved one's death may be very different depending on whether I opt for a religious or materialistic worldview. Interestingly, this is what van Fraassen (ibid. p.17) seems to have in mind when he defines philosophy as "the enterprise
in which we, in every century, interpret ourselves anew". This arguably satisfies the very human need to feel 'at home' in the world.
3. Having a worldview helps us to answer the crucial questions of what constitutes a well-lived life, and why. For all the talk of the impossibility of inferring an 'ought' from an 'is', it is impossible to shake off the intuition that how we ought to live intimately depends on the sort of thing we are and the sort of world we live in. That's why all the baroque metaphysics in Plato's Republic ultimately serves to answer the question, posed at the start of the book, what is the just life? Certainly, many of us already have strongly-held beliefs about the well-lived life prior to any metaphysical theorizing. Even so, having a worldview could give us a basis or a ground for such beliefs, answering the 'why' bit in the above question.
If I am right, then it seems that metaphysical inquiry is certainly worthwhile, despite the high risk of getting it wrong, and that, pace van Fraassen, metaphysics is not 'truth or nothing'. Such inquiry would still be constrained by the need to construct a worldview. But I take it that this constraint is much less restrictive than Ladyman's criterion, which would rule out controversies that humans have always cared about.