Thursday, October 28, 2010

TRSM's Shark Example 2

Sharks electrically detect things to eat and things that impede locomotion (Kalmijn, 1974). An edible living thing such as a flatfish differs in ionic com• position from the surrounding water, producing a bioelectric field partially modulated in the rhythm of the living thing's respiratory movements. A flatfish that has buried itself in the sand will be detectable by a shark swimming just above it. Reproducing the bioelectric field of the flatfish artificially, bypassing a current between two electrodes buried in the sand, invites the same predatory behavior. The shark digs tenaciously at the source of the field departing from the site when the act fails to reveal an edible thing (Kalmijn, 1971). Now there is no intelligible sense in which it can be claimed that the source ought to have appeared inedible if the shark's perception were free of error and if the shark's perception of affordances were direct. In the niche of the shark 'an edible thing' and 'electric field of, say, type F' are nomically related. To predicate of the shark (a) 'detects electric field of type F' and (b) 'takes to be an edible thing' is not to refer to two different states of affairs, one (viz. (b)) that is reached from the other (viz. (a)) by an inference. Rather, it is to make reference in two ways to a single state of affairs of the shark-niche system. The linking of (a) and (b) is not something that goes on in the "mind" of the shark, as the Establishment would have it. The linking of (a) and (b) is in the physics of an ecological world, namely, that system given by the complementation of the shark and its niche.
Third, consider TSRM's claim that "to predicate of the shark (a) 'detects electric field of type F' and (b) 'takes to be an edible thing' is not to refer to two different states of affairs, one (viz. (b)) that is reached from the other (viz. (a)) by an inference."  This, too, seems to me to be overstated.  "Detects electric field of type F" and "takes to be an edible thing" have different intentional or semantic contents (maybe both have intentional contents that differ or maybe (a) lacks intentional content, where (b) does not), so doing the detecting and doing that taking are not the same state of affairs in a perfectly pedestrian sense that EPists often admit. This is part and parcel of seeing something as an electric field (which would not seem to be an affordance) versus seeing it as an edible thing (which would seem to be an affordance).  In fact, part of the rationale for this shark experiment is to try to disentangle these different intentional objects--these different objects of perception.

Now, maybe there is some sense in which (a) and (b) are the same (which TSRM do not explicate), but there is a crucial sense in which they are different (which I have explicated).  This is why I temper my objection, noting that their claim is overstated.


  1. Er, the sense in which these are the same is in the last bit (from 'Rather,it is to make...'). This is applying the ecological laws analysis to this specific case.

    And the point is that, from this perspective, a and b are exactly the same thing. That's what it means for perception to be direct and bounded by ecological law.

    Are you worried that this just sounds like an unnecessary redescription?

  2. I'm worried about the implausibility of what appears to be implicit in this. (It's kind of unclear to me what is going on here.) Take a related claim. It is one thing to take something to be an electric field, but it is another to take something to be edible (even if these are nomologically correlated). Now, TSRM don't say that precisely. They claim that detecting an electric field is the same as taking there to be an edible thing.

    Or, here's another thing. One can see a car (detect a car), but that is not the same thing as seeing it as (taking it to be) a Honda S2000. This seeing vs seeing-as distinction is pretty standard stuff. It is what is underlying the experiment with the shark, I take.

    Gary earlier invoked a notion of "seeing-as", although I don't know if it is one half of this seeing vs seeing-as distinction that I am invoking.