We endorse Stanford's project, which calls attention to features of human psychology that exhibit a “puzzling combination of objective and subjective elements,” and that are central to cooperation. However, we disagree with his delineation of the explanatory target. What he calls “externalization or objectification” conflates two separate properties, neither of which can serve as the mark of the moral.

The objectification of moral norms is purported to occur because it enables correlated interactions between individuals who share the same cooperative norms. But how does this process take place? I suggest two mechanisms beyond those Stanford identifies. I also ask whether there is predictable variation in which moral norms engender the strongest coupling between objectification and discomfort with disagreement.

We argue that although objectivist moral attitudes may facilitate cooperation, they are not necessary for the high levels of cooperation in humans. This is implied by evolutionary models that articulate a mechanism underlying Stanford's account, and is also suggested by the ability of merely conventional social norms to explain extreme human behaviors.

We show that externalization is a feature not only of moral judgment, but also of value judgment in general. It follows that the evolution of externalization was not specific to moral judgment. Second, we argue that value judgments cannot be decoupled from the level of motivations and preferences, which, in the moral case, rely on intersubjective bonds and claims.

Stanford holds that the externalization and objectivization of moral judgments are what sustain human cooperative lifeways. We reply that the central function of human moral psychology is to track and respond to the structural features of our social environment, and we argue that moral obligations are grounded in the relationship between individual agents and the stability of their social groups.

To facilitate cooperation, moral externalization requires truthful and meticulous information about others’ moral commitments (Stanford target article, sect. 6). By definition, this information does not exist in the low-information environments where humans display their “hypercooperativeness.” Furthermore, collecting that information – if possible – entails costs that other mechanisms for correlated interaction avoid. Hence, moral externalization is an unlikely mechanism for cooperation, let alone “hypercooperation.”

We offer four counterarguments against Stanford's dismissal of moral externalization as an ancestral condition, based on requirements for ancestral states, mismatch between theoretical and empirical games, passively correlated interactions, and social interfaces that prevent agents’ knowing game payoffs. The fact that children's externalized phenomenology precedes their discovery of subjectivized phenomenology also suggests that externalized phenomenology is an ancestral condition.

It is worth distinguishing two phenomena involved in moral externalization: the experience of moral obligations as externally imposed and the tendency to generalize moral obligations. I propose that each played a distinct role in creating the conditions under which characteristically human cooperation could evolve.

Stanford argues that cooperators achieve and maintain correlated interaction through the objectification of moral norms. We first challenge the moral/non-moral distinction that frames Stanford's discussion. We then argue that to the extent that norms are objectified (and we hold that they are at most objectified in a very thin sense), it is not for the sake of achieving correlated interaction.

It is more likely that externalized morality that facilitated cooperation (externalized prosociality) was selected for versus other types of moral impulses. Recent research suggests that those other moral impulses may actually be at root prosocial, in that judgments about them are indirectly about avoidance of harm. Externalized prosociality may help explain why prosocial behavior benefits individuals.

Stanford casts original light on the question of why humans moralize some preferences. However, his account leaves some ambiguity around the relationship between the evolutionary function of moralization and the dynamics of tribal formation. Does the model govern these dynamics, or only explain why there are moralizing dispositions that more conventional modeling of the dynamics can exploit?

It is not clear how a moral demand alone can motivate an agent to exclude those who fail to act as the demand states. A more plausible hypothesis for the evolution of human moral cognition is based on seeing moral demands as subjective, but inherently conjunctive. This subjectivist-conjunctive proposal can still account for the apparent externalization of moral demands.

Stanford's goal is to explain the uniquely human tendency to externalize or objectify “distinctively moral” demands, norms, and obligations. I maintain that there is no clear phenomenon to explain. Stanford's account of which norms are distinctively moral relies on Turiel's problematic work. Stanford's justification of the claim that we “objectify” moral demands ignores recent studies indicating that often we do not.

That morality comprises a distinct and objective conceptual category is a critical claim for Stanford's target article. We dispute this claim. Statistical conclusions about a distinct moral domain were not justified in prior work, on account of the “stimuli-as-fixed-effects” fallacy. Furthermore, we have found that, behaviorally and neurally, morals share more in common with preferences than facts.

Most moral demands indeed are externally imposed, as violations are subject to social condemnation. While in modern society objectified moral demands may serve as a cue for desirable interaction partners, human morality evolved in small tribes that offered little choice regarding with whom to cooperate. Instead, it was adaptive to objectify moral demands to avoid the costs of social exclusion.

Encultured individuals see the behavioral rules of cultural systems of moral norms as objective. In addition to prescriptive regulation of behavior, moral norms provide templates, scripts, and scenarios regulating the expression of feelings and triggered emotions arising from perceptions of norm violation. These allow regulated defensive responses that may arise as moral idea systems co-opt emotionally associated biological survival instincts.

I extend Stanford's proposal in two ways by focusing on a possible mechanism of externalization: disgust. First, I argue that externalization also has value for solving coordination problems where interests of different groups coincide. Second, Stanford's proposal also holds promise for explaining why people “over-comply” with norms through disassociation, or the avoidance of actions that merely appear to violate norms.

A general feature of our moral psychology is that we feel that some moral demands are motivated externally. Stanford explains this feature with an evolutionary account, such that moral externalism was selected for its ability to facilitate prosocial interactions. Alternatively, I argue that a cognitive, non-selectionist account of moral externalism is a more parsimonious explanation.

I respond to the many thoughtful suggestions and concerns of my commentators on a wide variety of questions. These include whether moral norms form a unified category, whether they have a distinctive phenomenology, and/or whether moral normativity is a cultural construct; whether moral externalization is necessary for correlated interaction or human prosociality; precisely how such externalization generates correlated interactions among prosocial agents; and whether there are any convincing alternative explanations for it.

Many philosophers of science and methodologists have argued that the ability to repeat studies and obtain similar results is an essential component of science. A finding is elevated from single observation to scientific evidence when the procedures that were used to obtain it can be reproduced and the finding itself can be replicated. Recent replication attempts show that some high profile results – most notably in psychology, but in many other disciplines as well – cannot be replicated consistently. These replication attempts have generated a considerable amount of controversy, and the issue of whether direct replications have value has, in particular, proven to be contentious. However, much of this discussion has occurred in published commentaries and social media outlets, resulting in a fragmented discourse. To address the need for an integrative summary, we review various types of replication studies and then discuss the most commonly voiced concerns about direct replication. We provide detailed responses to these concerns and consider different statistical ways to evaluate replications. We conclude there are no theoretical or statistical obstacles to making direct replication a routine aspect of psychological science.