On Functions and Purposes

By Adam. J. Pearson

Photo: A pair of porcupines in their native habitat in Quebec  

We usually identify ‘purposes’ in nature both relatively and retroactively. Evolution selects for a particular trait and we end up noticing that it gave a species some edge over other species or previous forms of its own species in the long run. In retrospect, we say, the trait in question served a useful ‘purpose’ for the species that had it. The ‘purpose’ we note in this case is relative; to what? To the survival of the organisms that had the trait.

This is our retrospective perspective as human observers looking back on the developments of natural history and physical evolution. Most organisms do not share this retrospective assessment of the ‘purposes’ of their traits, however; their experience is much more rooted or grounded in their present experience.  The environment presents them with a particular challenge and they respond to it as best they can given the physiological equipment they have at their disposal. Their perspective is not retrospective, but present-centered; .they act spontaneously and responsively.

Humans have a tendency to act with intentions, goals, future outcomes, and reasons in mind; we think purposively, so we tend to also see purposes in nature.  Is this perception of ‘purpose’ an anthropomorphic projection onto nonhuman reality or an intuition into a real characteristic of other organisms in the nonhuman world? This is a difficult question to answer.  A squirrel digs in the ground and it pulls up a nut.  A human who sees this situation might say that the squirrel dug with the ‘purpose’ of digging up the nut.  The squirrel, if it could answer, might answer, on the contrary, that “I was hungry and I dug. And lo and behold, what did I find, but a nut!”

The human perspective sees future-oriented thinking at work; the squirrel perspective might perhaps see something more like a present response to a present need.  “I’m hungry and I dig and I find a nut,” says our conveniently talking squirrel. Humans connect the dots of causality; we say “the squirrel was hungry” SO it “dug.” “It dug” SO “it found a nut.” To the squirrel, however, the situation might look less like “x, so Y, Y, so Z” and more like “x and Y and Z.” I’m hungry AND I dig AND I find a nut. Is there purpose for the squirrel? Is their forward-looking goal-directed action or present-responding action going on for him?  Which is it? Could it be both?

‘Purpose’ is a difficult term to use as a tool for looking at the natural world beyond the human realm because it implies teleology, ‘final ends,’ the assumption that there are intelligent designs or purposes in nature.  This is probably why biologists tend to favour the less metaphysically-loaded word ‘function.’ Asking what is the function of a particular physiological adaptation, for instance, just means “what does it DO for the organism that has it here and now? What advantage does it provide?” The function of a porcupine’s quills, for instance, is to provide some sort of protection from predators for the creature; evolution favored the selection of this trait because those creatures that had it had a better chance of surviving than others that did not.

Does this presence of a clear function, however, mean that the porcupine’s quills have a ‘Purpose,’ a divinely-ordained role in the grand design of a Higher Power? Our answer will depend on our metaphysical stance. Christians and Muslims, for example, might say: “yes indeed; what we know from scripture leads us to believe that everything in Creation is the result of God’s Will and conscious Creation and is there for a particular divinely-prescribed purpose.”

In contrast, an atheist might reply that “what we know about the universe and the way evolution works does not require any sort of ‘purpose’ in this sense. It is enough to talk of functions that favour survival and evolution and evolution that favours the development of these functions.” How can we decide the issue once and for all? Perhaps we will never be able to finally decide the matter; we can assess the facts and the arguments we have and come to our own conclusion.  But there is no authoritative tribunal in the settling of truth and falsehood, especially when the questions at hand are philosphical in nature and their answers are not easily amenable to empirical falsification.

This is not to say, however, that we cannot identify clear ‘purposes’ in human life. Certainly, we have many. But ‘purpose’ seems to imply a conscious intention which, while prevalent in humans, is not always so easily locatable our brothers and sisters from other species. It is one matter to speak of the ‘function’ that certain minerals or organisms serve in a particular ecosystem, that is, what is the role that they play in the energy cycle that allows that ecosystem to flourish.  However, it is a very different matter to ask its ‘purpose’ in an abstract, future-oriented, divine plan-grounded sense.  That particular aspects of nature serve particular functions, all will agree; but that these functions have purpose is a point of great contention.


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