Pain signals are predominantly imperative


Recent work on signaling has mostly focused on communication between organisms. The Lewis–Skyrms framework should be equally applicable to intra-organismic signaling. We present a Lewis–Skyrms signaling-game model of painful signaling, and use it to argue that the content of pain is predominantly imperative. We address several objections to the account, concluding that our model gives a productive framework within which to consider internal signaling.

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Fig. 1


  1. 1.

    See Chalmers (1996), McGinn (1989), Tye (1995) for compelling statements of the problem.

  2. 2.

    There are significant differences in the pain contents that each of us has argued for in previous work. Such differences, though, are irrelevant to our current point, and we ignore them in what follows.

  3. 3.

    Such explicitness and clarity, while invaluable for our current exploratory purposes, come at a price: many problems that other psychosemantic theories, such as teleosemantics (Millikan 1984; Papineau 1987), tackle, are simply brushed aside in the Lewis–Skyrms models we will be relying on. For one important example among many, indeterminacy problems (Fodor 1990) do not arise in the first place. This is, we submit, as it should be: adding in the machinery necessary to deal with these issues would complicate the discussion, with no clear explanatory payback in the present context. In any event, we expect that the main lessons to be drawn from the present discussion will carry over to more complex accounts of mental content.

  4. 4.

    At least when messages are (partially) causally responsible for acts, as they are in the pain model we describe below.

  5. 5.

    It is possible to quantify the indicative/imperative information that single messages carry about single states/acts. For example, Skyrms (2010, p. 41) proposes that we quantify the information that message \(M_{i}\) carries about state \(S_{j}\) as

    $$\begin{aligned} \log \frac{\Pr (S_i|M_j)}{\Pr (S_i)} \end{aligned}$$

    and mutatis mutandis for individual acts. The weighted average of these individual contributions is the mutual information between messages and states (acts), which is what we have proposed using as a measure of the overall indicativeness and imperativalness of messages in a game.

  6. 6.

    Assuming that they are contentful at all. Messages might also be neither predominantly imperative nor indicative via carrying no information. As pains obviously do something, we will ignore this possibility in what follows.

  7. 7.

    That is not to say that partially pooling configurations never evolve in the game in Table 1. Huttegger et al. (2010, p. 183) report that the replicator dynamics in discrete time takes senders and receiver to a partial pooling equilibrium 4.7 % of the time. Our current point is, rather, that configurations in which there is imperfect information transfer (including the partially pooling ones reported by Huttegger and colleagues) are inaccessible, at least by the replicator dynamics, from an initial population structure in which the sender is being perfectly informative and the receiver pools perfectly, or vice versa.

  8. 8.

    Not always, however. Severe inflammation can cause persistent tissue damage, which singles it out as an important target for treatment; see Nathan (2002).

  9. 9.

    In the sense that there are other equilibria with the same expected payoff, but none with a better one. Whenever we speak of “a best-paying equilibrium” throughout the paper, this is what we mean.

  10. 10.

    More precisely, messages effect a partition of the set of posslble acts, but not of the set of possible states.

  11. 11.

    For historical presentations, we rely on Chap. 8 of Melzack and Wall (1996). For an updated presentation see Perl (2007).

  12. 12.

    Although, of course, only once we set aside the question of how phenomenology knows to match qualitative character to etiology, given those complexities.

  13. 13.

    There is some evidence that MPQ descriptors can be used to discriminate between particular pain syndromes, as detailed in Katz and Melzack (1999). This work focused on pathological syndromes, however, and used sets of descriptors to make discriminations among pathological syndromes. As such, there is little evidence that single dimensions of pain quality correspond in any neat way to the cause of pain.


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Financial support for this work was provided by the DGI, Spanish Government, research Project FFI2011-26853 (Martínez); Consolider-Ingenio Project CSD2009-00056 (Martínez); a Macquarie University Faculty Research Travel Scheme Grant (Klein); and Australian Research Council Grant FT140100422 (Klein). We would like to thank Murat Aydede, David Bain, Peter Clutton, Matt Fulkerson, the audience of the invited symposium “Painful Pains, Yummy Tastes, Stinky Smells: Sensory Affect” at the 2014 meeting of the APA Pacific in San Diego, and two anonymous referees for comments and suggestions on an earlier draft.

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Correspondence to Manolo Martínez.

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Martínez, M., Klein, C. Pain signals are predominantly imperative. Biol Philos 31, 283–298 (2016).

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  • Signaling games
  • Internal signaling
  • Pain
  • Imperativism