What is the consensus about 2N2C? Is there any broad consensus on its truth, or utility?

That's the fun abbreviated title of Boyd's No Non Causal Contribution (double N, double C) thesis, see Constructivism, Realism and Philosophical Method:

Here then is the insight necessary to an understanding of the metaphysical-innocence thesis: the sense in which realists and empiricists hold, while constructivists deny, the metaphysical import of conventionality in science is that constructivists affirm whereas realists and empiricists deny that in the relevant sense social conventions in science determine the causal structure of the phenomena scientists study. I add “in the relevant sense” because, of course, scientific (and other) conventions are a matter of human social practice and human social practices themselves have causal effects including causal effects on the causal structures scientists study.

Since this claim is philosophically uncontroversial, we should understand realists and empiricists as affirming and constructivists as denying the No Noncausal Contribution thesis (2N2C): the thesis that human social practices make no noncausal contribution to the causal structures of the phenomena scientists study. If the accommodation thesis is accepted, then 2N2C exactly expresses the metaphysical-innocence doctrine whose acceptance differentiates realists and empiricists from constructivists... My experience has been that philosophers’ reactions to 2N2C and the analysis of constructivism in terms of it are quite varied. Some have thought that a demonstration that constructivists must deny 2N2C would amount to a reductio ad absurdum of constructivism while others have thought the interpretation of constructivism offered here entirely fair to the philosophical intentions of constructivists.

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    I added a Boyd's quote and a reference since I doubt that most users know what 2N2C is. As is clear from the quote, there is no consensus on it, nor can there be a consensus (as is usual in philosophy), so you may want to rephrase the question
    – Conifold
    Commented Jul 19, 2017 at 1:06
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    I'm afraid I cannot comprehend the question, but I doubt there's a consensus even on the definition of the words being used.
    – user20253
    Commented Jul 19, 2017 at 13:02
  • "What is the consensus" is a bit of an odd frame here... (Maybe there's a specific interpretative problem in your reading here that you'd like to emphasize?)
    – Joseph Weissman
    Commented Jul 19, 2017 at 13:27
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    @JosephWeissman maybe to discussion based, but i wanted to read a short post informing me about the relevance of 2n2c today
    – user25714
    Commented Jul 19, 2017 at 13:33
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    @PeterJ Realists hold that what science reveals about the world is not "dependent" on our social practices. Since obviously our notations, conventions and even the language itself do so depend one has to factor these out of "what science reveals". That would be the "causal contribution" as opposed to epistemic contribution to the content of science. The 2N2C thesis is that this is all that social practices contribute, they are "metaphysically innocent". It is one way to frame what realists and social constructionists disagree about. But an answerable question is missing so far.
    – Conifold
    Commented Jul 19, 2017 at 20:41

1 Answer 1


My google search shows that there are no papers discussing 2N2C. The thesis at most was mentioned as a passing interest, never as a focal point. Also, Richard Boyd’ entry on scientific realism in SEP (https://stanford.library.sydney.edu.au/archives/spr2009/entries/scientific-realism/) was archived, and replaced by a different author (https://plato.stanford.edu/entries/scientific-realism/). The SEP decision should be right since the content of Boyd’s entry looks more like a propaganda of his own view of scientific realism. Given the lack of enthusiasm among philosophers of science and the cold reception within the SEP community, my guess is that Boyd’s 2N2C is not a popular concept, which has no conceptual utility and, if true, only trivially.

I myself had taken several graduate seminar courses offered by scientific realists (Ronald Giere at U of Minnesota and Nancy Cartwright at UCSD), but surprisingly never heard of Richard Boyd or his 2N2C. So I was curious why the thesis was unpopular.

Boyd asserts as follows in https://stanford.library.sydney.edu.au/archives/spr2009/entries/scientific-realism/

A realist rebuttal to [constructiivism of sophisticated sort, which he calls the Neo-Kantian constructivism] is available if one makes explicit, and defends, a piece of common, and philosophical, sense about the metaphysics of conventionality: the no non-causal contribution thesis (2N2C). According to 2N2C, human social practices make no non-causal contribution to the causal structure of the world, and are in that way metaphysically innocent.

Surprisingly, Boyd never really unpacks that strangely worded thesis. And it turns out that he appeals to two other theses which he also assumes innocent: the the metaphysical-innocence thesis and the accommodation thesis.

Having read Boyd’s article, I have to say that his argument for scientific realism by way of 2N2C is unpersuasive. I find three glaring problems in Boyd's theory.

  1. circularity

Boyd’s argument for scientific realism (scientific entities exist independently of us, and also have causal role phenomenally) looks circular due to the fact that the theses are posited without support. He states they are “philosophically uncontroversial.” I am suspicious whether he can hold the three theses consistently (I will not pursue this line of thought for the lack of time)

  1. indistinguishability

Boyd’s argument for scientific realism ended up being indistinguishable from the stance of scientific anti-realism (= empiricism). The above theses are shared by both empiricists and realists, a la Boyd. His target being constructivism, Boyd ends up being an ally of anti-realism.

  1. wrong target

Boyd makes a wrong target for scientific realism. Boyd should have focused on attacking empiricism (=anti-realism), not constructivism.

P.S. I look forward to seeing a defense argument for 2N2C.


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