The earthworm and the thermostat

An earthworm is an example of a simple entity that seems clearly to demonstrate purposeful behavior and some form and degree of sensitivity -- we might balk at ascribing consciousness to it, but it doesn't seem like an impossible stretch to imagine that it actually "feels" in some way. Whether or not this is actually the case depends, according to the argument here, on its neurophysiology, or on how its simple behavioral options are connected to its simple sensory inputs. If input is directly connected to output – that is, if its behavior consists just of reflex arcs – then we can at least say that it has no need of feeling. But if its neural inputs, however crude (sensitivity to temperature, nutrients, light perhaps) are instead connected to an intermediate neural structure that modulates and "represents" the external stimuli, and if there is another neural structure that is able to use these representations, however simply, in order to determine behavior, then we might very well say that the earthworm does indeed "feel", because some level of phenomenal awareness would then be required as the means of connecting the two intermediate neural structures.

This is just saying again what was said below, but relying upon at least a plausible intuition that even a very simple mobile organism can feel. But now let's consider a thermostat, a control device that also exhibits what might be called "purposive behavior", though only with a certain amount of metaphorical licence since in this case the mechanism involved is very obvious: a thermometer falling below a set level triggers a switch to start a furnace. Nevertheless, here we have another case, like the earthworm, of a simple entity that receives environmental input and determines its behavior in light of that input. Suppose that we complicate the thermostat a bit by adding another input channel besides temperature – perhaps a clock, say, or a light-meter, so that the triggering termperature can be set lower after a certain time, or with the onset of darkness. How would these two "sensory" inputs work together? One way – perhaps the more likely way – would be to connect both directly to a more complicated switch that relied upon a double trigger to start the furnace. But another way – perhaps a more flexible way – might be to connect both inputs not directly to the switch but to an intermediate layer, where their signals could be represented as qualitatively distinct "tokens" on a linear scale – and then to make a second layer out of a simple processing chip that could accept these tokens as input and determine upon its "behavior" – whether or not to start the furnace – based upon its processing of these inputs. In this case, would we be as tempted to say of the thermostat what we were of the worm – that, in some fashion and to some degree, it "feels"?

Well, perhaps not, and for a number of reasons, some of them good ones – such as the fact that the thermostat is a special purpose device whereas the worm is an autonomous entity, and much more complex than even this artificially complicated thermostat. But this is also a test of our intuition in this entire area, and, just as the intuition that the sun revolves around the earth mislead us in the past, so might the sense that even quite simple evolved organisms can feel, but even quite sophisticated designed ones cannot, be a mere prejudice.