Friday, August 19, 2005

Flexible Content

In this post I want to explore the relationship between plasticity and intentional content. Intentional explanations are a form of causal explanation (we're claiming that those mental states caused that behaviour), and as such commit us to certain modal claims, (different mental states would have led to different behaviour). We can thus use counterfactuals to illuminate our ascriptions of intentionality.

The distinction between robust-process and actual-sequence explanations is especially helpful here. To quote Kim Sterelny ('Basic Minds', pp.207-208):
Distinct explanations of the same event can both be important, for they can convey distinct breeds of modal information. In earlier work I have used the origins of World War I to illustrate this idea. This time, I illustrate it through a more significant conflict, Australia's victory over England in the 1974-5 cricket tests. One explanation of this victory would walk us through a play-by-play description of the tests, detailing each dismissal, run by run and out by out. An alternative would appeal to the strengths and weaknesses of the opposing sides: in particular, Australia's strengths in fast bowling and fielding. These two explanations do not conflict, and each is of value. The play-by-play explanation is an actual-sequence explanation, for it identifies the particular possible world that we inhabit. But if it is true that Australia in that series was much the stronger side, we could know the precise sequence of plays without knowing something very important. Namely, had Australia not won that way, they would have won in another and similar way, with the fast bowlers taking most of the wickets, often to spectacular behind the wicket catches. A robust-process explanation compares our world to others. It identifies an important class of counter-factuals. It identifies the feature characteristic of the worlds in which Australia triumphed in the series.

Sterelny continues: "When representations are causally relevant, they will be relevant as part of robust-process explanations of behaviour." Thus he thinks the key question, when attempting intentional explanations of animal behaviour, is to ask: what tracks the possible worlds in which this behaviour occurs? With basic "reflex-like organisms", the answer will be some simple sensory cues. For example, ants identify corpses to drag out of their nest by the oleic acid produced by the decaying process. Apply this chemical to a live ant, and nestmates will carry it away, despite its lively struggles! The behaviour is dominated by the stimulus, rather than mediated by a more flexible internal representation (which we may assume would be open to contrary evidence, recognizing that real corpses don't struggle, etc.).

So Sterelny insists that "robust tracking", i.e. using multiple cues to identify a property, is a necessary condition for genuine representation. Ants don't have any mental representations of death or corpses, they merely react to the stimulus of oleic acid in their environment. Allen and Hauser, in their 'Concept Attribution in Nonhuman Animals', similarly hold that to have a concept of X, "[o]ne must have a representation of X that abstracts away from the perceptual features that enable one to identify X's." Because the chemical signal is generally reliable, ants are able to identify dead nestmates. But because of the inflexibility of this single-cue tracking, we should say that the ants to not recognize the corpses as dead. They have no concept of death -- no "internal representation of death that is distinct from the perceptual information that is used as evidence for death."

Building on this foundation, Allen and Hauser go on to propose two general empirical tests to detect animal concepts. First, their behaviour must be sufficiently flexible, using multiple cues to form decoupled representations which in turn impact upon a wide variety of behaviours. Second, animals should be able to revise "what they take as evidence for an instance of that concept" -- giving less weight to cues that they've recently found to be unreliable. If ants had a concept of death, they should have become suspicious of oleic acid after experimenters started splashing it over their live nestmates. The next time they detected it, they should have checked for some other signs of death before starting the funeral march. That's what creatures with concepts would do.

I'm not entirely sure what to make of all this. It seems possible to simply respond to inflexibility by saying that ants have brittle detection mechanisms which mean we can manipulate them into having false "beliefs". Just spray some oleic acid, and ants will think the target is a corpse! It will always be logically possible to save an intentional explanation by insisting that the creature's representations are simply false, unreliable, or impervious to contrary evidence. So it seems we will need to appeal to some sort of simplicity principle, and refuse to accept ad hoc intentional ascriptions unless the evidence clearly warrants it.

J. Bennett too, in 'How to Read Minds in Behaviour', appeals to a form of plasticity. If we find an animal behaving similarly (e.g. giving warning cries) in response to a wide variety of diverse stimuli, we should want to unify this behaviour under a single explanation. He writes:
Even if no one sensory kind of stimulus is shared by all the episodes... they may have something in common that lets us generalize across them, namely the fact that each of them provides evidence to the animal that there is a predator nearby. If they share that, and there is no more economical way of bringing them under a single generalization, that gives us evidence that the episodes are united in that way for the animal itself. That is tantamount to saying that in each episode the animal thinks there is a predator nearby... We get at belief content through what is perceived as common to all the environments in which the behaviour occurs. [bold added]

Then again, even if we grant that the ants do not represent death, why not say that they represent the presence of oleic acid? After all, that is what's "common to all the environments in which the behaviour occurs". I guess it's the simplicity argument again: postulating a mental representation here is unnecessary, and adds nothing to our explanations. Further, there is the principled objection that the stimulus exhibits 'tyranny' over behaviour, which indicates a lack of internal cognitive processing.

Heyes and Dickinson utilize many of the ideas discussed above in 'The intentionality of animal action'. If an action is caused by a belief-desire pair, then we may suppose that the action would not have occurred had either of those mental states been lacking. This generates two critera for intentional ascriptions. The belief criterion requires that "[t]he behaviour must be sensitive to whether or not environmental contingencies will support a belief with the appropriate causal content." The kicking and screaming ants did not support the belief that they were corpses, so we shouldn't attribute any such belief to the manipulated nestmates. (Heyes and Dickenson concede that creatures aren't always perfectly rational, but we need to assume something like it for practical reasons. Otherwise we'd have no basis at all on which to ascribe mental content. We need there to be a reliable connection between mental content and behaviour.) Their desire criterion is that "the performance of the action adjusts appropriately to manipulations designed to alter the desire for the outcome." But they grant that this is especially difficult to manipulate in any controlled way (i.e. without causing further, unintended consequences).

I actually don't think the Heyes and Dickinson criteria are especially helpful. Suppose a creature tracked a functional property (say, food) via multiple cues, which were generally quite reliable, but there was some further cue that they were incapable of detecting. We might trick them using a dummy which presented all the former cues and lacked only the latter -- which (suppose) strikes us as a very crucial and obvious cue, the lack of which would "clearly" mean the belief is unsupported. Here it seems a mistake to say the animal lacked beliefs about the functional property. The fact that it was robustly tracked by multiple cues seems sufficient -- the belief doesn't have to be absolutely foolproof. Judgments of whether some situation "supports" the belief or not is surely relative to the discriminatory abilities of the creatures involved. What beliefs are reasonable for a blind man might not be so reasonable for a sighted person to hold in that same environment.

But then, what if the ants are simply "blind" to the struggles of the pseudo-corpse? The movements impact upon their senses, sure, but if their perceptual systems don't pick up on this as relevant, passing the information along to "central cognition" (if such exists in ants), then isn't this equivalent in principle to simple blindness? If the presence of oleic acid is the only relevant environmental datum that the ant is capable of fully perceiving, can we still hold that a belief about the "corpse" is "unsupported" by the environmental contingencies? Here I find Allen's ideas in 'Mental Content' helpful: he points out that's it's fine for individuals to make the odd mistake, or to occasionally fail to distinguish between two properties (e.g. being dead, and being marked with oleic acid) -- humans do it all the time (e.g. gold vs. "fools gold"). But if one was entirely incapable of making the distinction, in any possible circumstances, then one does not have the concepts. Ants cannot possibly identify corpses independently of oleic acid, therefore they have no concept of death as distinct from the perceptual information they use as evidence for it.


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