Fred Dretske. Photo courtesy of Stanford University.
Dretske: why operant conditioning is evidence for belief and agency in animals
Earlier, when discussing Dretske's (1999) article on machines, plants, animals and agency, I suggested that there were actually two criteria in his article which he used to distinguish between organisms with and without beliefs. I examined his first criterion of learned flexible behaviour, and found that it could not account for three cases (conditioning of the autonomic nervous system (ANS) in an astronaut, of leg withdrawal in cockroaches, and of flexion of the hind legs within the spinal cords of paralysed rats) where learned flexible behaviour appears to occur in the absence of beliefs. Additionally, Dretske seemed to employ the terms "mindless", "unlearned" and "hard-wired" inter-changeably.
However, Dretske used another, more rigorous criterion for distinguishing organisms that have beliefs and exhibit agency from those that do not: the capacity to undergo operant conditioning, a form of learning which he links to the notions of representation and control:
Dretske Mark II
Learning of this sort (operant conditioning) consists in harnessing these internal representations to control circuits so that behaviour will occur in the external conditions on which its success depends
(1999, p. 10, italics mine).
How are we to understand Dretske's claim that operant conditioning can be understood in terms of internal representations linked to a controlled behavioural response? Two readings are possible. On a "maximalist" reading (which I shall defend below in my model of operant agency), an organism with beliefs is one that can use its internal representations of its environment, acquired through learning, to control its surroundings. The verb "control" is here meant to describe an action, performed by an agent. (On this account, the concept of agency needs to be further developed.) An alternative "minimalist" reading (which appears to be Dretske's own view) is that operant agency is simply behaviour which is controlled by an organism's internal representations of its environment. Here, "controlled by" simply means "caused by".
Dretske's account of representation is a thorough-going naturalistic, causal account, which eschews appeal to "interpreters" as the arbiters of what counts as a representation. Representations, on his account, are indicators which carry information about lawlike connections (say, between As and Bs), but they are something more. Representations, unlike indicators, can be mistaken, because they have a function which they can fail to perform. More precisely, representations are indicators whose natural function is to indicate as they do, because doing so confers a selective advantage on the organism possessing them. Representations, unlike other natural indicators, are not hard-wired: they acquire a function or meaning for an animal only when the animal learns what they indicate. An animal's learning history imparts a meaning to its experiences. Belief-type representations are recruited as causes of bodily movements in an animal because the animal learns what they indicate. Thus beliefs are both reasons and causes of actions (Ryder and Martin, 1999, pp. 5-7; MacFarlane, 2003; Pitt, 2002). This explains Dretske's (1999) contention that while behaviour may have a meaning, purposeful acts are governed by their meaning, insofar as events cause an animal to behave in a certain way, by virtue of their meaning.
Thus in Dretske's case of the bird that shuns the Viceroy after tasting a similar-looking noxious Monarch butterfly, the bird's internal representation causes the avoidance behaviour precisely because it means something about its external environment (i.e. that a certain kind of butterfly is present - the sort of butterfly the bird, after its unpleasant experience, wants to avoid).
It would be beyond the scope of this thesis to adjudicate between competing theories of mental representation (summarised in Pitt, 2002). What is important here is that in Dretske's account (unlike Abramson's, which was discussed above) internal representations play a causal role in operant behaviour. It is also significant that Dretske's account highlights the evolutionary history of representations, which confer a selective advantage on their possessor.
Dretske's account of belief: a critical evaluation
Despite these positive features, I believe that Dretske's account of belief is not powerful enough, on its own, to distinguish organisms with beliefs from those without.
First, his account fails to distinguish operant behaviour from mere instrumental conditioning, which (Conclusion L.12) can occur even in the absence of belief. We looked at three such cases above. Dretske might claim that in these cases, the systems involved are not forming representations. But in fact, the astronaut's ANS is representing its external environment, and its function is undeniably a natural, biological one. Moreover, some kind of learning is going on: in space, the astronaut's ANS learns not to compensate for loss of blood to the brain when she stands up, and once the astronaut returns to earth, her ANS has to re-learn this skill. Why does this not qualify as operant conditioning?
To add to the confusion, Dretske's own example of the bird that shuns the Viceroy is not a very clear example of operant conditioning. According to Dretske, the bird believes that the Viceroy tastes unpleasant, and I would certainly agree with him that this ascription of belief to the bird is correct and natural. But in this case, the bird can hardly be said to be engaging in operant behaviour, properly speaking: it is merely avoiding an object that resembles a noxious stimulus. (Abramson would classify this as instrumental behaviour.) One could explain the bird's change of behaviour using a mind-neutral goal-centred intentional stance, according to which memory can be understood simply as stored information, and learning as a process by which the bird, as an educable animal, acquires new information that enables it to alter its behaviour patterns.
Finally, Dretske's minimalist account fails to explain why behaviour controlled by representations has to be envisaged in mentalistic terms. For Dretske, "controlled behaviour" appears to be synonymous with behaviour caused by representations - defined as learned connections between As and Bs, which serve a biological function. But causation per se is not a mentalistic notion. Likewise, Dretske's notion of representation is too weak to sustain mentalistic inferences. For him, the decisive features of representations are that they carry information which indicates something about the world, they confer a selective advantage on their possessor and they are learned. As we have seen (Conclusions I.1, B.4, I.3, L.11), these properties are necessary conditions but not sufficient warrants for the ascription of mental states.
R.2 The presence in an organism of Dretskean representations, defined as indicators acquired through learning which serve a biological function, does not provide a sufficient warrant for our being able to ascribe cognitive mental states to it.
Despite these problems, I believe Dretske's account of belief lies very close to the truth, because it brings together vital ingredients of belief: flexible behaviour, learning, internal representation, and the possibility of error (mis-representation). The limitations of Dretske's account might be remedied by adopting a richer notion of representation. In my model of operant agency in insects, I shall argue that representations have a distinctive internal structure, drawing upon several themes that have been discussed in this section: action selection, fine-tuning, control, trying, associations, means and ends (goals). I shall also argue that this rich structure also elucidates the notion of control, linking it to agency, and allows certain kinds of representations to serve as beliefs through which agents control their actions.
It remains to examine one more criterion that has been proposed as the hallmark of belief: the possibility of self-correction.
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