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Sharing a Smile

Smiles have been much studied in the behavioural sciences. Can understanding smiles help us to see objections to philosophical theories about joint action, and about action?

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What Is a Smile?

What distinguishes a genuine smile from a muscle spasm or the exhalation of gas through the mouth which might produce things resembling smiles? Consider this answer: only the genuine smile is a instrumental action.

Why think of the smile as instrumental? Because smiling is a skillful activity requiring sustained coordination of zygomatic major and orbicularis oculi muscles that is typically learned through social interactions in the first year of life (Messinger & Fogel, 2007, pp. 335--7, 348--50; Reddy, 2000). If you think about how smiles can unfold (becoming increasingly wry, say), how they mesh with other expressions of emotion (your shock becomes amusement before, as the Ayesha’s trick with your distant ancestor’s favourite antique vase goes horribly wrong, turning to horror), how they combine with winces and blinks and other facial expressions (Fridlund, 2014, p. 177), how they are responsive to context,[1] and how they can be used to express not only amusement but also happiness, politeness, satisfaction or playfulness among other things, you can see that smiling is not always a matter of simple and instant muscle contractions.[2] Further, like grasping an object or articulating a particular phoneme, smiling is an action that can be realised by different sequences of bodily configuration in different contexts.

You might object that smiling cannot be an instrumental action because it does not happen to bring an outcome about. But the smile itself is the outcome. The goal of the action is to simile that smile (Something similar applies in the case of grasping and producing a phonetic gesture.)

Smiles present Obstacles to solving The Problem of Action

As instrumental actions, smiles create obstacles for many attempts to solve The Problem of Action. Although sometimes produced intentionally, a genuine smile can be something unexpected and even unwanted to the agent (as when you fail to supress a smile that would be inappropriate).[3] People also smile in their sleep; accoring to Messinger & Fogel (2007), newborn infants smile on average every 5 minutes during sleep. Smiles are this difficult actions to accommodate whether you adopt the Standard Solution or prefer an Anscombian alternative.

One view is that what makes an event a smile, a instrumental action and not just a muscle spasm caused by excess wind, is the way that motor representation is involved. Specifically, the genuine smile will involve a motor representation of the outcome, the smile, and this motor representation will lead to movements by way of planning-like motor processes.

Sharing a Smile is a Joint Action

So far I've suggested that smiling is a instrumental action, the goal of which is to smile that smile. Next I want to consider sharing a smile. You and I sitting together at the performance observe a clown’s falling. As the initial shock of seeming to witness a terrible accident turns to joy, we turn to each other and share a smile. As the lights go up, we smile together at the clown hoping that they will see us and be rewarded by our smile.

In the first moment, sharing a smile is a dyadic interaction; in the second moment, we are jointly smiling at the clown. These are both apparently joint actions. So we can ask,

[The Smile Question] What distinguishes joint actions such as sharing a smile from parallel but merely individual actions as when you and I each individually smile at the clown’s performance but nothing is shared between us? (See The Question.)

Could Bratman’s account of shared intention (see Bratman on Shared Intentional Action) enable us to answer the Smile Question? If not, is this a reason to revise or reject that account?

Is it plausible that sharing a smile involves any kind of commitment to smiling? If not, can we hold on to the view that all joint action involves commitment (Gilbert, 2013)?

Consider how we might attempt to answer the Smile Question.

Merely being in the same situation is not enough for us to be sharing a smile.

Minimally, there have to be two kinds of connection between us for us to share a smile.

First, bodily coordination: the way your smile unfolds is shaped to some degree by how mine unfolds and conversely.

Second, emotional coordination: in sharing a smile, we are to some extent emotionally tied together. To some extent, the way your amusement unfolds is being controlled by, and controlling, the way mine unfolds. (This is why you might occasionally regret sharing a smile with a stranger.)

Attempts to characterise joint action by invoking one or another kind of shared intention do not appear well-placed to capture these features.

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motor representation : The kind of representation characteristically involved in preparing, performing and monitoring sequences of small-scale actions such as grasping, transporting and placing an object. They represent actual, possible, imagined or observed actions and their effects.
Standard Solution : (to The Problem of Action). Actions are those events which stand in an appropriate causal relation to an intention.
The Problem of Action : What distinguishes your actions from things that merely happen to you? (According to Frankfurt (1978, p. 157), ‘The problem of action is to explicate the contrast between what an agent does and what merely happens to him.’)


Azuma, T., Shimizu, A., Yamashita, K., Iwase, M., Kajimoto, O., Tatsumoto, Y., & Sumitsuji, N. (2016). The Inappropriate Smile and Zygomatic Muscle Activity: Perceptual and Motor Skills, 92(2).
Frankfurt, H. G. (1978). The problem of action. American Philosophical Quarterly, 15(2), 157–162.
Fridlund, A. J. (2014). Human Facial Expression: An Evolutionary View. Academic Press.
Gilbert, M. P. (2013). Joint commitment: How we make the social world. Oxford: Oxford University Press. Retrieved from
Haggard, P. (2005). Conscious intention and motor cognition. Trends in Cognitive Sciences, 9(6), 290–295.
Hursthouse, R. (1991). Arational actions. The Journal of Philosophy, 88(2), 57–68.
Messinger, D., & Fogel, A. (2007). The interactive development of social smiling. In Advances in child development and behavior, Vol. 35 (pp. 327–366). San Diego, CA, US: Elsevier Academic Press.
Reddy, V. (2000). Coyness in Early Infancy. Developmental Science, 3(2), 186–192.
Schmidt, K. L., Cohn, J. F., & Tian, Y. (2003). Signal characteristics of spontaneous facial expressions: Automatic movement in solitary and social smiles. Biological Psychology, 65(1), 49–66.


  1. Although smiles as a whole exhibit variability depending on context, they may also involve characteristic movement patterns which could provide the basis for recognition in observers. Schmidt, Cohn, & Tian (2003) offer evidence that ‘the onset phase of spontaneous smiles [... have] consistent temporal characteristics, despite many differences in the contexts and conditions under which these smiles were elicited.’ ↩︎

  2. This is dramatically illustrated by the social complications of impariment to the ability to smile appropriately in schizophrenia (Azuma et al., 2016). ↩︎

  3. A related source of obstacles arises from what Hursthouse (1991) calls arrational actions. Note that her category of arrational action does not include smiles that are not intentional actions. ↩︎