Keep in mind that there is nothing obviously wrong with assuming that human concepts are complex and composed in some way; that assumption cannot, as indicated, be ruled out on Fodor's grounds. It is also independently plausible because (ignoring for good reasons Fodor's (
1998
,
2008
) very
speculative and externalist-driven accounts of how ‘atomic’ concepts could be acquired) composition offers the only viable acquisition alternative. If so, let us assume some kind of ‘guided’ compositional clustering operation that, so far as we know, could be shared with animals. Then let us look elsewhere for an explanation of the uniqueness of human concepts. One plausible line of inquiry is looking to the features that make up
human conceptual capacities (+/–ABSTRACT, POLITY, INSTITUTION, and so on) and inquiring whether at least some of them are likely to be duplicated in animals’ concepts. It is difficult to be confident when speaking of the conceptual capacities of animals, but there is, I think, reason to doubt that they do or that – if they do – they are capable of employing what they have. While humans might describe and think of a
troop of Hamadryas baboons as having a single form of male-dominant ‘government’ in their social system, it is unlikely that the baboons themselves would think of their form of social organization at all, much less think of it as one of a range of possible forms of political/social organization – authoritarian patriarchic tribal hierarchy, cooperative democratic system, plutocracy, matriarchic statist-capitalist economy . . . Olive baboons are of their natures matriarchal; Hamadryas baboons are definitely not. And even if a troop of Hamadryas baboons should through loss of dominant males become matriarchal, it is not as if the remainder of the troop deliberated whether to become so, and chose to. It appears that they have nothing like the capacity for abstractness afforded routinely in our notions of social institution, or for that matter classes of fruit that include a wide range of different species. Nor could Hamadryas or olive baboons or any other ape think of their organization and the territory over which they have hegemony as we do. Where we can think of London as a territory and set of buildings
or
as an institution that could move to another region, nothing in ape behaviors or communicative efforts exhibits this ability to adopt either, or both, ways of thinking. Nor likely could any think of their territories in the following way: “London [the volume of air in its region] is polluted” or “London [its voting population] is voting Conservative this time.” Their concepts for their organization (assuming they have such) and for the territories over which they have hegemony just do not allow for this, nor would either be seen as a species of more general cases (POLITY?) that would invite speculation about whether they could re-organize in a different way, and plan to do so if they decide to. Further, and perhaps most important, if an ape should have or ever develop a concept analogous to our RIVER – say, RIVER
B
(‘RIVER-for-a-variety-of-baboon’) – its concept's features would very likely be restricted to those that can readily be extracted from sensory input, and its use would be restricted to meeting current demands, not allowing speculation about what one can expect to find in particular forms of geographic terrain. In a similar vein, it is hard to imagine a chimp developing a homologue to human concepts such as
JOE SIXPACK, SILLIEST IRISHMAN, or – for that matter – SILLY and IRISHMAN. In addition, on at least some plausible views of the lexicon and the meaning-relevant information it contains, mental lexicons must provide in some manner what are called “functional features,” such as TNS for tense (thought of syntactically and structurally) and several others that play roles in the composition of sentential concepts. These, clearly, are not in an ape's repertoire, and they certainly count as ‘abstract.’
The scope of animal concepts appears to be restricted in the ways that animal communication studies of the sort found in the work of
Gallistel and others indicate. To emphasize points made above: their conceptual features do not permit them to refer to the class of fruits, to forms of social institution, to rivers as channels with liquids that flow (distinct from creeks, streams, rivulets, etc.), to creatures such as humans, donkeys, and even ghosts and spirits with psychic continuity, to doors as solid and apertures, and so on. Rather, their concepts appear to involve
ways of gathering and organizing sensory inputs, not abstract notions such as INSTITUTION, PSYCHIC CONTINUITY, and the like that have dominant roles in human concepts. No doubt they have something like a ‘theory of mind’ and can respond to the actions of conspecifics in ways that mirror their own action (and deceit, etc.) strategies and routines. However, there is no obvious reason to assume of them that they understand a conspecific in terms of its executing action plans (projects), deliberating what to do next, and the like. That requires symbol systems that provide for ways of organizing concepts in the ways humans can, given language. Do they think? Why not? We say computers do, and it is apparent that little but usage of the commonsense term “think” turns on that. But can they think in articulated ways provided by boundless numbers of sententially organized concepts? No. Their lack of Merge indicates that.
Another line of inquiry – suggested obliquely above – notes that
human linguistically expressed conceptual packages allow for the operations of affixation in morphology, and for dissection when they appear at a semantic interface in a compositional sentential structure. The concept FRUIT expressed by the relevant morphological root gets different treatments when subjected to morphological variation: one gets
fruity
(which makes the associated concept abstract and adjectival),
fruitful
(dispositional notion),
fruitiness
(abstract again),
fruit
(verbal),
refruit
(produce fruit again), etc. So far as I know, no other creature has concepts that provide for the relevant kinds of morphosyntactic ‘fiddling.’
As for dissection: when one encounters sentences such as
Tom is a pig
(where Tom is an 8-year-old child), the circumstance of use and the structure of the sentence that predicates being a pig of Tom require for interpretation that one focus on a (usually small) subset of the features commonly taken to be piggish, treating these as the ones ‘called for’ by a specific state of Tom.
If he is wolfing (another metaphor) down (still another) pizza, GREEDY is likely to be one of the features dissected from the others and employed in this circumstance. Human languages and the concepts that they express provide for this kind of dissection, and the desire for
creativity in use routinely exhibited in metaphor depends on it. Perhaps animals have complexes of features for PIG. It is unlikely, though, that they have GREEDY (an abstract notion applied to more than pigs) or that their cognitive systems are equipped to easily dissect one part of their PIG concepts from others and apply that part to a situation, as is common with constructions that call for metaphorical readings. I assume that dissection applies only at an interpretational interface, SEM. Until that point, as indicated, a lexical item's semantic features can be thought of as carried along in a derivation as an atomic ‘package.’ Arguably, however, an animal's concepts remain functionally atomic all the way through whatever kinds of cognitive operations are performed on it. What is known about animal communication systems, and about the limited degree of flexibility in their behaviors, environments, and organization, suggests this.
The last two lines of inquiry, and to a degree even the first, point to the fact that the human conceptual materials contained in mental lexicons have properties that might be contributed by, but are certainly exploited by, the compositional operations of a uniquely human language faculty. Were these
properties of human conceptual materials ‘there’ before the introduction of Merge, were they instead invented anew only once the system came into place, or rather do they consist in ‘adaptations’ of prior conceptual materials to a compositional system? I do not attempt to answer that question: I know of no way to decide it one way or another, or to find evidence for a particular proposal. Clearly, however, the concepts humans express in their languages – or at least, many of them – are unique to humans.
I should mention one endless class of concepts that plausibly does depend on Merge. Apes and other creatures lack recursion – at least, in the form found with language. If they lack that, then – as Chomsky suggests – they lack
natural numbers. So NATURAL NUMBER and 53, 914, etc. are all concepts unavailable to other creatures.
5
There is plenty of evidence of this. While many organisms have an
approximate quantity system, and their approximations respect Weber's Law (as do very young children's), only humans with a partially developed language system have the capacity to enumerate (assuming that they employ it: for discussion, see p. 30). Only humans have the recursive capacity required to develop and employ a number system such as that found in the natural number sequence. Specifically, many organisms can reliably and in short order distinguish sets of objects with 30 members from
those with 15, and with accuracy that decreases in accordance with Weber's Law, sets of 20 from 15, 18 from 15, and so on. However, only humans can reliably distinguish a set with 16 from one with 15 members. They must count in order to do so, employing recursion when they do. The work of Elizabeth Spelke, Marc Hauser, Susan Carey, Randy Gallistel, and some of their colleagues and students offers insight and resources on this and some related issues.
To summarize: ‘exact’ number concepts aside, it is difficult to draw on the
demonstrated human uniqueness of Merge as it is currently understood to explain why human concepts are unique. We found a more promising way to proceed in the apparently human-specific natures of many of the semantic features that compose human concepts – the fact, for example, that humans even at an extremely young age seem to have the
feature PSYCHIC CONTINUITY built into their concepts for a wide range of organisms, and definitely for humans. Whether this approach ultimately proves successful and explains the difference is unclear. It is reasonably clear, however, that human conceptual resources are indeed
unique.