Saturday, August 20, 2005

Drives and Preferences

Let's distinguish two kinds of motivating states. On the one hand are non-representational drives, such as lust or hunger. They're pure 'affect'/emotion/sensation. Then there are preferences, which have representational content: they represent some 'goal' state of affairs that the animal deliberately aims to bring about.

Why is this important? Sterelny (TiaHW, pp.92-95) argues that, like decoupled beliefs, preferences increase an organism's adaptive plasticity, improving their ability to make apt decisions when faced with a broad range of possible responses.

For one thing, some biological goals are too complex to be captured by a purely sensory/affective drive (p.94). Consider social status in primates. There is no simple pattern of sensory stimuli common to all status-raising goal states for a biological drive to latch on to. Instead, the animal needs to be sensitive to a wide range of social relations, unified by functional properties that can only be tracked by way of abstract representation (cf. the Bennett quote).

Further, Sterelny suggests that drive structures are "winner-take[s]-all control systems" (p.93) -- "the strongest drive determines the action chosen, and at that point the other drives are epiphenomenal." To balance different motivators appropriately requires representation. (I'm not entirely sure why - there seems an air of stipulation about this.) When acting on your strongest preference, you can alter your behaviour in light of your other (lesser) preferences.

This would make sense if pure drives are defined as leading to involuntary/automatic action. Sterelny writes, "We digest, breathe, and vary out heartbeat rate without any cognitive representation of the metabolic needs these activities service." ('Situated Agency and the Descent of Desire', p248.) But our eating behaviour is more flexibly controlled, which I guess means that we act on a representation of our internal hunger drive, rather than the drive itself? We can certainly modify our eating behaviour in light of our other goals, so the behaviour isn't the result of any simple competitive drive hierarchy, at least.

I take it the idea behind this is that to engage in practical reasoning about a goal (e.g. sating one's hunger), one must represent that goal to oneself. Otherwise one couldn't reason about it, relating our beliefs about some possible state of affairs with our preferential ranking of that possibility. Drives are brute action-drivers, whereas preferences can combine with beliefs to produce more informed action.

Can beliefs combine with drives to produce intentional action? They might be guided by 'implicit beliefs' or information within the organism. But 'driven' action is not, I take it, a product of reflection or rational processes taking place within anything resembling 'central cognition'. (Otherwise I'm really confused about what "drives" are supposed to be.) Any such deliberative action must instead be motivated by preference-representations of the drives, rather than the drives themselves.

Does that sound right?


  1. If you go trekking in the woods in California, you are advised by the authorities to wrap your food tightly in a plastic bag each night, and to hang this bag from a rope tied to a high tree branch some distance from your campsite. This advice is to avoid bears stealing your food and possibly attacking you in the process.

    But the bears of Californian national parks now know that people do this, so they mostly no longer attack campsites. Instead, they look in trees near to the campsite for ropes, and, finding such ropes, climb the associated tree to get at the plastic bag of food. This change in the bear's behaviour has happened within living human memory, arguably too soon for it to be an evolutionary adaptation.

    My question is this: The bears have clearly developed a plan of action in order to achieve their goal, and then modified this plan in the light of changing environmental circumstances. If these were humans we would call this process of planning and re-planning practical reasoning. Is it practical reasoning when bears do it? If so, do bears maintain representations of their goals?

    None of us know, of course (and maybe we can never know), but it would seem to be perfectly possible that bears do NOT have any representation of goals. Yet they seem to engage in (something which looks identical with) practical reasoning about their goals.

  2. I'm not sure how to explain the bear behaviour without appeal to goal-representations. For information registered by the bear (i.e. its 'beliefs') to impact on its behaviour in such a complex and flexible way, they must be tied to its motivation systems somehow -- and goal representations seem the obvious answer. (That's not to say the bears need be conscious of it.) How else would you explain it?


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