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Neo-positivist metaphysics


Some philosophers argue that many contemporary debates in metaphysics are “illegitimate,” “shallow,” or “trivial,” and that “contemporary analytic metaphysics, a professional activity engaged in by some extremely intelligent and morally serious people, fails to qualify as part of the enlightened pursuit of objective truth, and should be discontinued” (Ladyman and Ross, Every thing must go: Metaphysics naturalized, 2007). Many of these critics are explicit about their sympathies with Rudolf Carnap and his circle, calling themselves ‘neo-positivists’ or ‘neo-Carnapians.’ Yet despite the fact that one of the main conclusions of logical positivism was that metaphysical statements are meaningless, many of these neo-positivists are themselves engaged in metaphysical projects. This paper aims to clarify how we may see a neo-positivist metaphysics as proceeding in good faith, one that starts with serious engagement with the findings of science, particularly fundamental physics, but also has room for traditional, armchair methods.

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  1. Quotes above are from Chalmers et al. (2009), Ladyman and Ross (2007), Maudlin (2007), and Van Fraassen (2002).

  2. I am going to be singling out and attempting to characterize one particular version of neo-positivist metaphysics in this essay. Chalmers (2009) and Hirsch (2009) are other metaphysicians who voluntarily take on the ‘Carnapian’ label. These views seem to me to be aimed at bringing into the twenty-first century a different form of positivism than that with which I am concerned here.

  3. See the discussion of ‘There are material objects’ below.

  4. Assuming, that is, that such claims are true at all in that system.

  5. As an historical claim about Carnap’s views, this statement is somewhat confusing since ‘physicalism’ today is used differently than Carnap used it. Carnap himself was aware of the ambiguity in the term. It will help to note the following. When Carnap says ‘physicalism,’ he usually has in mind not a metaphysical claim but the view that unified science should be formulated in one particular language: physical language. And when he says ‘physical language,’ he does not mean simply whatever language is used in physics. Rather, he means a language that uses terms for objects in space and time (Carnap 1934, p. 54). More on this distinction in a moment.

  6. Following the comments in the preceding footnote, Carnap would want to say that physicalism (in the contemporary sense) is compatible with both physicalism (in Carnap’s sense of the word) and phenomenalism. The latter two positions are alternatives about how to formulate the claims of physics.

  7. This is probably as good a place as any to make a note about something I have ignored in the main body of the text. This is that the method for neo-positivist metaphysics I am proposing really only explicitly concerns how one should settle one’s fundamental metaphysical commitments, and this is why the science that this method takes to inform metaphysics is fundamental physics. This leaves open the question of whether or how one should choose a derivative, i.e. non-fundamental metaphysics. I try to address this issue elsewhere in my work on reduction.

  8. Allan Hazlett has suggested I call this method of coming to believe (in) only what is common to all formulations of our current physical theories the Intersection Method.

  9. Note that this does involve in one sense at least siding with Carnap against Quine. Quine, recall, argued that we don’t even have objective, not-merely-pragmatic standards of verification within science. So, Quine was a pragmatist about all matters, not just metaphysical matters. The present view depends on rejecting such a global pragmatism. Science can provide us with objective justification for its claims.

  10. This is another place where I am not sure I agree with Quine, and what Field (1980) takes to be the metaphysical upshot of his reformulation of physics in Science Without Numbers.

  11. Thanks to an anonymous referee for this journal for raising this issue.

  12. This is not to say that the debate between phenomenalism and physicalism (in today’s sense) does not come up at all. My view is that this comes up at a later stage as will (I hope) become clear in the next section.

  13. There is a lot more discussion to be had on this issue of what versions of physical theory should inform metaphysics. One further reason in favor of the stance I take above has to do with the positive contribution of metaphysics vis-à-vis physics I discuss at the end of the paper. I will return to this issue there.

  14. Another matter altogether concerns the fact that many philosophers of science are anti-realists about scientific theory. To these philosophers, even if the scientists themselves think their theories are aiming to accurately represent the world, this itself is incorrect (e.g. Van Fraassen 1980). This philosophical issue (in contrast to the sociological issue discussed above in the text), about realism versus anti-realism deserves (and has received, though not by the present author) much discussion elsewhere. As should be clear from this essay, I side with the realists.

  15. One topic I don’t engage here is the role of idealization in science. Even if scientific theory discusses ideal gases and frictionless planes, we shouldn’t as metaphysicians accept such things into our ontology. My assumption is that it should be clear from the scientific theories themselves which representational elements correspond to idealizations and which do not. Perhaps the fiction of an ideal gas is indispensable to physics (though probably not to fundamental physics), nevertheless the existence of one will not be.

  16. The suggestion is that the neo-positivist adopt an expressivism about those metaphysical claims that are not justified by the indispensability arguments analogous to what Blackburn (1984) and Gibbard (1990) offer for ethical claims. Price (2011) argues, for broadly positivist reasons, that we should adopt such an expressivism about all metaphysical claims. Unlike Price, I think that the justification physics gives us for some fundamental metaphysical claims does provide grounds for rejecting such a global expressivism, even if does support a more local version.

  17. See Albert and Ney (forthcoming) for more details on rival formulations of quantum mechanics and their metaphysical ramifications.

  18. The view I am describing is that associated with a certain prominent class of Bohmians and is further explicated in Dürr et al. (1992), Allori et al. (2008), and Albert and Ney (forthcoming).

  19. Here I am glossing over the fact that there is not really a univocal way the Everettian wants to understand the wave function. I am only trying to outline here one prominent approach.

  20. See Ney (forthcoming) for discussion of this issue.

  21. See Belot (forthcoming) for discussion of this issue.

  22. Here again, however, the issue of truth and justification is raised. This is something French and McKenzie do not address. When metaphysicians develop their theories of, say, what composition is or in what circumstances it occurs, or what a law is, is it possible using armchair methods to come to justified conclusions about these matters? Here again, perhaps neo-positivist will argue that such justification depends on the verdicts of our best scientific theories (what do all theories say composition is or a law is), or that here when armchair metaphysicians support this or that theory, they are only expressing a preference.

  23. For more on this topic, see Greaves (2007).

  24. At least this how physics justifies its endeavors to the world-wide community. For example, the following comes from CERN’s website for its Large Hadron Collider (LHC): “Why? A good question… This is CERN’s core business. With the LHC the aim is to continue to push our understanding of the fundamental structure of the universe.” See

  25. Note, coming back to the earlier discussion about which versions of current physics should inform metaphysics, that for metaphysics to play this positive role, it must be engaging with real versions of physical theories taken seriously by the physics community.

  26. And many have argued that the B-theory is indispensable to any theory that is going to obey special relativity.

  27. How much evidence, or whether the acceptance of scientific theories even proceeds in the way assumed here, is another issue.

  28. See the essays in Galison and Stump (1996) which may be viewed as a kind of polemic for constructing models of the world that are complex in many ways, emphasizing pluralities over unities.

  29. This has been a recurring theme in Dennett’s work: “In most sciences, there are few findings more prized than a counterintuitive result. It shows something surprising and forces us to reconsider our often tacit assumptions. In philosophy of mind, a counterintuitive “result”… is typically taken as tantamount to a refutation. This affection for one’s current intuitions, sometimes amounting… to a refusal even to consider alternative perspectives, installs deep conservatism in the methods of philosophers. Conservatism can be a good thing, but only if it is acknowledged.” (2005, p. 34 my emphasis).

  30. Interestingly there are a class of cases for which Paul concedes this. Sometimes, she notes, there is an issue that it is really up to science to settle, but science isn’t far enough along yet to be able to settle it. Here Paul argues that the metaphysician is free to construct models so long as she realizes that she doesn’t have the justification to argue the views she comes to are true (Paul 2012). I am in agreement with Paul on this point. I would just argue that the same applies to the cases described in the preceding paragraphs.


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I would like to thank audiences at the 2011 Pacific APA, the University of Bristol, and the University of Edinburgh for helpful discussion. I’d also like to thank an anonymous referee for Philosophical Studies for helpful criticism on an earlier draft and conservations with Allan Hazlett and James Ladyman.

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Correspondence to Alyssa Ney.

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Ney, A. Neo-positivist metaphysics. Philos Stud 160, 53–78 (2012).

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  • Metametaphysics
  • Metaphysics
  • Neopositivism
  • Indispensability arguments