Today here at University of Puerto Rico Mayaguez, our English Department is hosting the annual meeting of the College English Association/Caribbean Chapter. The conference topic is "animals."I think I'm going to lay out my whole thesis for The Minds of Animals. Come to think of it that's impossible, because I'll get to speak for maybe fifteen minutes before a really random ten minutes or so discussion. So I need to focus.
Start with the idea of the semantics of (intentional) psychology. If "belief" and "desire" are nouns, subjects of sentences, then what are the referents of those words? There are several theories on offer. My view is that, regardless of which of the available leading theories of mind one chooses, there is a presumption that you mean for your theory to be a general theory of psychology, one that could be used to understand both the simplest and most complex instances of "mind" (Hume, the godfather of empiricist psychology, was insistent on this point: if it doesn't apply to dogs and babies, then it isn't basic enough.) Thus behaviorism, for example, tried to make the internal, unobservable referents go away: it is an example of an "eliminativist" view of mental representation. On a behaviorist semantics for psychological nouns, they refer to sets of behavioral tropes (thus "fear of dogs," "believes they have chocolate at El Amal," "happy," and so forth). On this view there is no argument for distinguishing psychological descriptions of humans from those of other non-human animals. Note that the behaviorist is deeply committed to a deflation of the human mind to something that is put together from relatively simple processes. (Not that I'm criticizing behaviorism: that's what I think is good about it. Or at least, I'm intrigued that behaviorists at least have a novel strategy for dealing with "mental representation" and "intentionality"). Finally, this is an example of an internal argument: I'm not interested in disproving behaviorism, only in the consistent treatment of the theory.
The same argument applies to an altogether different model of psychological explanation, that of what is now called "evolutionary psychology," or back in the day "sociobiology," what one can think of as a sort of (my coinage) adaptive determinism. The idea is that the cause of the behavior (and for that matter of the thought or of the feeling) is the operation of genetic or more generally evolutionary causes. Thus an article a few years back in the New York Times laid out a Steven Pinkerish argument more or less as follows: Your dog acts as if it loves you, thus soliciting an affectionate response from you, because the dog is adapted to living off of you: all is instinct. My brother-in-law confronted me with this article. The response is to point out that on any reasonable interpretation of evolutionary, one could replace the word "dog" in the story with "baby," and the argument would be equally good: of course your baby is adapted to elicit an emotional response from you, of course that involves "genetic programming," whatever that is. That doesn't mean that the vocabulary of "loves you" and "pays attention to you" and "has a relationship with you" is somehow an illusion. This is to confuse the "why" with the "how." More importantly we get the same result as before: for evolutionary psychology, as for behaviorism, someone who actually embraced the theory as the right account of the semantics of intentional explanation provides no reason to apply one interpretation to humans and another to non-human animals.
The situation is more complex when we look at cognitivism, post-behaviorist psychology that focusses on mental representation, language, and the formal organization of cognition. Chomsky argued that a defining trait of humans was a capacity for "generative grammar," the ability that the parts of language give to generate an indefinitely large (demonstrably infinite, in fact) set of potential sentences. Thus generative grammar could be interpreted as a reason to make a distinction between humans and non-human animals in terms of the mental states that we attribute to them respectively. Davidson refined the model of intentional states as "propositional attitudes," and he explicitly states that on his view, language-capable beings can be rightly said to possess beliefs, desires, hopes, etc. And Fodor and his followers think that the syntactical structure of language may be the bridge between the semantic content of the mental and some kind of formal physical properties (of the nervous system, say). The issue here is about the relationship between thought and language. My initial response is intuitive: thought and language are not, as the cognitivists would have it, a chicken-and-egg pair. Thought must predate language by a very long way. Nervous tissue is older than bone tissue: our neurons and those of invertebrates are more similar in structure than most of the rest of us. The question here is whether we will come to see "mental representation," somehow understood, as a ubiquitous and ineliminable feature of animals with nervous systems, or we will come to understand nervous system function in a way that no longer refers to mental content. I really don't know which way that will go, but I doubt that it will turn out that human thinking is different in any radical way from that of many non-human animals. As to the rejoinder that we can just look and see that humans are cognitively very special, my response is that we won't find out much more about that if we start off with an ill-conceived insistence on some sort of fundamental difference.