Biology Reference
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genotype, of which X is the phenotypic expression to be selected by natural
selection' (Neander, 1998, p. 319). But this is not how I want to proceed.
My main difficulty with this formulation, at least for now, is the problem it
raises for thinking about how function, understood as a property internal to a
biological structure, might have first arisen, particularly in the light of recent
arguments that it almost certainly emerged prior to the onset of natural selection.
In other words, natural selection, as conventionally understood, requires the prior
existence of stable, autonomous, and self-reproducing entities, e.g., single-celled
organisms or, simply, stable, autonomous cells capable of dividing. But these
first cells were, of necessity, already endowed with numerous subcellular entities
(or modules) endowing the primitive cell with the functions minimally required
for the cell to sustain itself and reproduce. In other words, even if the first
cells lacked many features of the modern cell, they had to have had primitive
mechanisms to support metabolism, cell division, etc.; there needed to have
come into being primitive embodiments of function that would work keep the
cell going and protect it from insult.
What do I mean by function? Let me try to clarify my meaning by taking
off from Michael Ruse's argument against the sufficiency of circular causality
(Ruse, 2003). Ruse offers the familiar example of the cyclical process by which
rain falls on mountains, is carried by rivers to the sea, evaporated by the sun,
whereby it forms new rain clouds, which in turn discharge their content as rain.
The river is there because it produces or conveys water to form new rain clouds.
The rain clouds are a result of the river being there. But Ruse argues that we
would not want to say the function of the river is to produce rain clouds, and
he is right. What is missing, Ruse claims, is the means by which 'Things are
judged useful.' I will not follow Ruse in his deployment of such worrisomely
adaptationist notions as 'value' and 'desire'. Instead, I want to salvage Ruse's
observation by redescribing his 'judgment' as a measurement of some parameter
or, if you like, as an evaluation that is performed by a mechanical sensor and,
when exceeding some preset limit, is fed back into a controller which is able to
restore the proper range of parameter. In other words, I use the term function
in the sense that Nagel and Beckner did, i.e., in the sense of the first of Bill
Wimsatt's enumerations: a simple feedback mechanism. Like a thermostat. As
Wimsatt (2002, p. 177) puts it, 'To say that an entity is functional is to say that
its presence contributes to the self-regulation of some entity of which it is a part.'
Once such a mechanism is added to the rain-cloud-river cycle (say, a mechanism
that triggers a change in evaporation rates when the water level falls too low) we
can, in this sense of the term, legitimately speak of function and say, e.g., that
the function of such a mechanism is to maintain the water level within a certain
range of parameters. Furthermore, I argue, we can similarly refer to the many
different cellular mechanisms (proofreading and repair, chaperones, cell-cycle
regulation) that function to maintain various aspects of cellular dynamics.
