In his introduction to Thom Scott-Phillips\u2019s Speaking Our Minds, Olivier Morin mentioned my review of the book in the TLS. For reasons of length I could not include more substantive objections to chapters 3 and 4 of Thom\u2019s book in that review. However, since the gaps in his argument undermine his claim to have explained why humans but not apes acquired language, I don\u2019t think the issues are trivial. While I develop some of these points elsewhere (see the footnote for details), since some of those papers are not yet out, this discussion seems like as good a place as any to point out the reservations that I have with some of the central claims of the book.<\/p>\n
Central to Scott-Phillips\u2019s explanation of why humans alone evolved language are, he claims, two cognitive abilities: the ability to act with and understand fourth order meta-representations, and the ability to distinguish between \u2018informative\u2019 and \u2018communicative\u2019 intentions. Scott-Phillips argues that humans but not apes acquired language because they possess both of these abilities in ways that apes do not. I don\u2019t think this claim is defended adequately in his book.<\/p>\n
As I mentioned in the review, there is currently no evidence that pre-verbal infants could understand fourth order meta-representations. Indeed, there is evidence \u2013 not discussed in the book \u2013 that some six-year-olds struggle to entertain even second order meta-representations (Perner & Wimmer, 1985). Scott-Phillips appeals to the existence of O\u2019Grady et al. (2015) to show that human adults can entertain seventh-order meta-representations. However, since this ability may be a function of their language acquisition and not a pre-requisite of it, and since Scott-Phillips\u2019s claim must be true of pre-verbal children if it is to support his conclusions, the O\u2019Grady study just doesn\u2019t tell us what we would need to know.<\/p>\n
This takes us to the discussion of the significance of the informative-communicative distinction. According to Scott-Phillips\u2019s view, ostensive inferential communicators (including pre-verbal children) must be capable of each of the following:<\/p>\n
(1) the expression of informative intentions<\/p>\n
(2) the recognition of informative intentions<\/p>\n
(3) the recognition of communicative intentions<\/p>\n
(4) the expression of communicative intentions<\/p>\n
I won\u2019t say anything about (1), (2) and (3) here. (There is more to be said about each one, but that may require a great deal of further unpacking. For example, there now exist data for (3) that show inconsistent roles for ostensive cues in both human and ape gesture interpretation; and while I agree with Thom\u2019s empirical claims about (1), I would have liked to see more theoretical support for the benchmark that he sets.) However, I do want to raise some issues with this discussion of (4), understanding of which Thom takes to be manifested in engaging in hidden authorship. I found his handling of this point to be disingenuous.<\/p>\n
On Scott-Phillips\u2019s view, which he repeats in his 2015 Current Anthropology paper, it is a pre-requisite of grasping the informative-communicative distinction that one should be able to act with hidden authorship, since that requires recognising the significance of the ability to inhibit one\u2019s communicative intention.<\/p>\n
He supports the claim that pre-verbal children could distinguish between informative and communicative intentions by pointing to his own hidden authorship study (Grosse et al., 2013) on children. Although he refers to the subjects in this study only as \u2018children\u2019, the youngest children tested in this study were three years old, and so the study does not show that pre-verbal children are capable of hidden authorship in the way that his argument requires. It is not appropriate to draw conclusions about what pre-verbal children can do based on the abilities of three-year-olds. Indeed, when he and Gerlind Grosse ran their hidden authorship study in Leipzig at the end of 2009, they presumably also did not expect that preverbal children would show hidden authorship in their paradigm \u2013 since they did not attempt to test any children younger than three. It is a problem throughout Thom\u2019s book that he is inattentive to the ages of subjects when making claims about human ontogeny.<\/p>\n
The fact that Scott-Phillips over-interprets his own hidden-authorship data might be more forgivable if he did not also claim that the absence of evidence of apes performing well in the same paradigm should be interpreted as an \u2018implicit collective acknowledgment\u2019 by primate researchers that apes would fail the task. I agree with him that in this case, they probably would. However, since we don\u2019t even know whether pre-verbal human children would succeed in this paradigm, it\u2019s hard to know how to interpret this. I am sceptical that they would do so \u2013 but I also think this inconsequential, since hidden authorship is the wrong marker to use (Moore, 2015; under revision). Moreover, I am troubled that Scott-Phillips interprets an absence of evidence favourably in humans but unfavourably in apes, despite having reasons to doubt that the finding would really be present in pre-verbal children.<\/p>\n