I have received a few email messages from folks who think I haven't given enough attention to the flaws in Tomasello's research, which point to at least three major problems.
The first problem is that the results of Tomasello's experiments are mostly negative in emphasizing what chimpanzees and other apes cannot do by contrast with human beings. Such negative results leave us wondering whether this comes from some failing in the methodology that prevented the apes from showing their true abilities. Once people like de Waal try out a new methodology that produces positive results for the apes, it's not clear that Tomasello's research with negative results has much interest.
The second problem is that Tomasello's experiments comparing chimpanzees and human infants are dubious because they are conducted mostly with human experimenters, which creates a disadvantage for the chimps. It is easier for human infants to demonstrate their social skills when dealing with a human experimenter than it is for chimps to do this when dealing with a member of another species. We should expect that the full complexity of chimp social intelligence will be manifested only within chimp groups.
The third problem is that Tomasello's negative results often contradict what researchers are seeing among chimps in the wild. So, for example, de Waal's latest experiments showing chimp prosocial behavior conforms to what researchers like Andrew Whiten and Christophe Boesch have already seen among chimps in the wild in Africa.
The fundamental difficulty running through all of this is that in comparing human beings and other apes, we need to explain both the similarities and the differences.
. . . I am among those who are regularly accused of "raising the bar" on chimpanzees; that is, as soon as we discover that something we thought was a human-chimpanzee difference turns out not to be (e.g., understanding goals), we then posit something else as different and uniquely human (e.g., social imitation, normativity). But this raising of the bar results from the simple fact that there are observable differences between chimpanzee and human societies in terms of such things as complex technologies, social institutions, and symbol systems, and those most be explained. If some hypothesis about these differences is wrong, then it is rightfully consigned to the trash heap. But then we must come up with some new hypothesis to explain the difference--and there is a difference.("Postscript: Chimpanzee Culture, 2009," in Laland and Galef, eds., The Question of Animal Culture, 220)
Despite their apparent disagreements, De Waal ultimately has to agree with Tomasello that we must explain the uniqueness of human beings as well as their continuity with other apes. One can see this in what de Waal says about the evolution of morality in Primates and Philosophers. He refers to his experiments on "inequity aversion" among monkeys as showing "a sense of social regularity" or "monkey fairness" (44-45). But then he concedes that this falls short of the full human sense of morality:
Before we speak of "fairness" in this context it is good to point out a difference between this and human fairness, though. A full-blown sense of fairness would entail that the "rich" monkey share with the "poor" one, as she should feel she is getting excessive compensation. Such behavior would betray interest in a higher principle of fairness, one that Westermarck . . . called "disinterested," hence a truly moral notion. This is not the sort of reaction our monkeys showed, though: their sense of fairness, if we call it that, was rather egocentric. They showed an expectation about how they themselves should be treated, not about how everybody around them should be treated. At the same time, it cannot be denied that the full-blown sense of fairness must have started someplace and that the self is the logical place to look for its origin. Once the egocentric form exists, it can be expanded to include others. (48-49; cf. 20, 22, 54-55, 77, 168, 172)
So even as he stresses the continuity of human beings and other primates, de Waal recognizes the uniqueness of the human sense of fairness, which is based on the human capacity for abstract social cognition that extends care for oneself to care for an expanding circle of others. He says that "this rather abstract yet still egocentric concern about he quality of life in a community is what underpins the 'impartial' and 'disinterested' perspective" (172).
To me, this sounds a lot like what Tomasello is saying when he stresses the uniqueness of the human capacity for "shared intentionality," which supports the normative rules and customs of human social institutions, and thus going beyond the behavioral traditions of animal cultures.
No doubt, some of these issues will go into the next version of my "Primate Politics" course at NIU.