affordances in external reality, vs. algorithms

Damien Broderick (
Tue, 12 Oct 1999 18:01:46 +0000

At 12:40 AM 11/10/99 -0400, Matt wrote:

>I view concepts like causality, duration, weight, etc. in the same
>way. They don't have to be hard coded - they are learned because they
>are so useful under the universal physical constraints imposed upon
>all human beings.

This is the argument developed classically by James J. Gibson. Much information is coded into the world, so we don't need to represent it internally, just access it. (Although obviously in order to *think* about the world, *some* kind of reliable inner mapping is needed.) Here's a bit from my book THEORY AND ITS DISCONTENTS that cites Howard Gardner's useful THE MIND'S NEW SCIENCE on the matter:

While transcendental intuition of essences can no longer be regarded as an even remotely plausible explanation for the way we categorise the world and function within it, might it not be that mental symbols - coded as arbitrarily as any Saussurean might wish - crystallise on an innate grid? Impressive neurological evidence for this possibility is discussed in Jean-Pierre Changeux (1986). For Jerry Fodor (whose theories guide neurophysiologist Changeux's anatomical investigations), `people are born with a full set of representations, onto which they can then map any new forms of information that happen to emerge from their experiences in the world' (Gardner's precis, p. 83). If this is so, we parse the world according to the syntax of the language of thought.

The immediate objection, no doubt, is to gaze incredulously at the uncurbed plenty of human culture - an easy task if, as I do, you live in a neighbourhood where athletic women in brief garments jog past their faceless Muslim sisters each encased in something like a linen letterbox - and wonder if Fodor has had a restricted upbringing. But from the standpoint of cognitive research, the differences of mental structure between theologian Hans Kung and a !Kung San sorcerer are doubtless infinitely less compelling than the gap between the thought processes of human and chimpanzee, though we share more than 99 percent of our genetic coding with those ape-cousins.

Yet alternative views continue to be pressed powerfully. For the late James J. Gibson and his empirical followers, Fodorian representational models are simply unnecessary. In Gardner's summary:

[O]rganisms are so constituted, and live in a world so constituted, that they will readily gain the information they need to survive and to thrive. In particular, our sense organs are designed to pick up information from the external world. [...T]here is no need to operate upon it or process it; there is no need to draw on prior knowledge, on mental models, on interpretive schemata. (pp. 308-9)

If the Gestalt school argued many decades ago that we see what we do because our biology makes us look for patterns, Gibson turned the tables and asserted that the densities of texture and gradient in the world, a world we move through at will, provide all the cues we need to thrive in it. In short, we are organisms adapted by evolution to this world. Its *affordances* - `potentialities for action inherent in object or scene' (p. 310) - are its meanings. `Invariance in the ambient optic array,' Gibson claimed, `is not constructed or deduced; it is there to be discovered.' It is a position in harmony with philosopher Roy Bhaskar's `transcendental realism', though hardly with any version of high {poststructuralism].

See. eg, Gibson, THE ECOLOGICAL APPROACH TO VISUAL PERCEPTION (1979, Houghton-Miflin).

Damien Broderick