Tomasello argues that children's developing sense of obligation towards collaborative partners and in-group members develops within joint collaborative activities. Although we agree that the human sense of obligation is evident in collaborative activities, we believe that certain aspects of Tomasello's discussion can be extended to the case of testimonial learning. However, recent evidence that children treat epistemic and moral responsibilities distinctly suggests that the behaviors children use to hold others accountable may differ depending on the type of obligation or commitment that has been broken.

In addition to Tomasello's argument that there is a sense of obligation in moral cooperation, testimonial exchanges can also allow speakers and listeners to make commitments to each other, showcasing epistemic cooperation. In other words, learning from testimony depends not only upon monitoring speakers for signs of knowledge or competence (for a review, see Harris et al. Reference Harris, Koenig, Corriveau and Jaswal2017), but also upon recognizing those with willingness to cooperate and fulfill their commitments to tell the truth. In fact, much philosophical research on the role of trust in testimonial learning has argued that when addressees believe what they are told, take a speaker's word for it and trust her for the truth (Ross Reference Ross1986), they recognize the speaker's commitment to the truth of what she says (Moran Reference Moran2005), receive a unique kind of epistemic warrant to rely on that speaker (Holton Reference Holton1994) and can hold the speaker epistemically responsible as a result (McMyler Reference McMyler2011). In other words, when addressees believe something based on a speaker's authority, their trust is grounded in a mutual regard between the speaker and the addressee, which is similar to Tomasello's “second-personal responsibility” in joint collaboration. Similar to Tomasello's view that breaches of obligations can result in reactive attitudes (e.g., blame, protests), contemporary epistemologists also argue that listeners who accept a speaker's claim acquire a suite of rights, including rights to hold speakers accountable, rights of complaint, rights to demand an apology, and rights to forgive (Gilbert Reference Gilbert1992; Hinchman Reference Hinchman2005; McMyler Reference McMyler2011). Moreover, if addressees take someone “at her word,” they are entitled to pass responsibility back to the speaker when their belief is challenged, if they so choose (i.e., “pass the epistemic buck,” Brandom Reference Brandom1994; Goldberg Reference Goldberg2006).

Consistent with work in philosophy, a growing body of developmental research suggests that in testimonial exchanges that involve forms of commitment, children engage in a battery of behaviors that parallel those described by Tomasello in the domain of action. Tomasello describes that the human sense of obligation to collaborative partners manifest in (1) reactive attitudes when the partner fails to play her role in a joint commitment; (2) leave-taking behavior when breaking a commitment; and (3) fairness and reciprocity among second-personal agents. Similarly, when a speaker intentionally offers incorrect information in direct testimonial exchanges, even infants detect, interrupt, and actively correct speakers who make mistakes either by misnaming common objects (Begus & Southgate Reference Begus and Southgate2012; Grassmann & Tomasello Reference Grassmann and Tomasello2010; Jaswal Reference Jaswal2004; Koenig & Echols Reference Koenig and Echols2003; Pea Reference Pea1982) or by presenting difficult or anomalous requests (e.g., “Can you bring me the refrigerator?”; Grosse et al. Reference Grosse, Behne, Carpenter and Tomasello2010; Shwe & Markman Reference Shwe and Markman1997; Wellman et al. Reference Wellman, Song and Peskin-Shepherd2019). Not only can children direct objections at deviant speakers, they also actively protest against addressees who fail to fulfill the commands of a speaker (Rakoczy & Tomasello Reference Rakoczy and Tomasello2009), demonstrating an early understanding of the cooperative roles of both parties in testimonial exchanges. As for the analogy of children's “leave taking” behavior, recent evidence reveals that children trust a speaker who acknowledges her ignorance and a speaker who is accurate at similar rates, but reject information from an inaccurate speaker who acts as though listeners should believe her false claims (Kushnir & Koenig Reference Kushnir and Koenig2017). It is possible that after hearing a speaker acknowledge her ignorant state of mind, children credit the speaker for clarifying her epistemic limits. Thus, compared to an inaccurate agent who fails to do so, children are more likely to trust the previously ignorant speaker for new information. Further research suggests that children's reciprocity towards speakers is also similar to that of cooperative activities. Indeed, young children prefer to share more resources with accurate informants over inaccurate ones (Ronfard et al. Reference Ronfard, Nelson, Dunham and Blake2019), and choose to reciprocate with informative communicative partners over speakers that intentionally withhold information (Dunfield et al. Reference Dunfield, Kuhlmeier and Murphy2013). Together, these lines of research suggest that children hold others not only morally responsible, but also epistemically responsible.

Tomasello argues that children display various behaviors indicative of their understanding of obligation in joint intentional collaboration. Do these behaviors differ depending on the type of commitment that has been established? Recent work suggests that children may evaluate moral and epistemic commitments differently. For example, an agent's failure to uphold a spoken agreement reduced children's decisions to wait for future rewards and their willingness to share with that agent, but did not affect their willingness to learn new information from her (Pesch & Koenig Reference Pesch and Koenig2018). Likewise, although an in-group member's antisocial behavior reduced children's liking of and willingness to share with her (which is consistent with Tomasello's review of children's understanding of moral obligations within their in-group), children's decisions to seek new information from (Hetherington et al. Reference Hetherington, Hendrickson and Koenig2014) or imitate (Wilks et al. Reference Wilks, Kirby and Nielsen2018) the in-group member were not attenuated. Work like this suggests that a breach in moral obligations may not affect children's evaluations of whether the agent can fulfill their epistemic obligations (and vice versa).

In conclusion, we think that various aspects of Tomasello's obligation account can be extended to the case of testimonial learning, and that children likely treat testimonial transactions as implicating distinctively interpersonal commitments and responsibilities. Appreciating the shared nature of epistemic responsibility between speakers and listeners opens new opportunities for future empirical research to identify the various devices used by speakers to commit themselves to the truth of what they say, and the ways in which children detect epistemic commitments and violations in their decisions to trust.