trpmb6 wrote:. . . it seems to me that the word "purpose" inherently implies there is a concerted effort to achieve whatever that purpose is. Ie. for something to have purpose, it must first have been given a defining role by something sentient.
I think there's room in the definition of "purpose"
to allow for absence of a sentient actor. There are lots of effects driven simply by physics where a state of balance is the eventual outcome, and it's common in such situations to refer to an out-of-equilibrium system as having a goal or purpose of regaining balance.
trpmb6 wrote:Lightning, for instance, has no purpose. It is simply the effect of some cause we don't fully understand.
Trees have no purpose. They are simply there because that's what the environment and evolution allowed. The fact that they produce oxygen as a byproduct of their existence does not imply that their purpose is to produce oxygen.
Lightning is the perfect example of what I mentioned above. It can be accurately stated that lightning serves the purpose of dissipating unbalanced electrical charges. I doubt there's anyone with a conscious goal of evening out the charges in clouds for the vast majority of lightning (barring the occasional Dr. Frankenstein).
Your tree example is more interesting; the purpose of photosynthesis (i.e. the reason why it's selected for in plants) is to transform energy in sunlight into a more useful chemical form, which is useful from an evolutionary standpoint as a survival strategy. I believe you could even say that a tree's purpose in sprouting leaves and photosynthesizing sunlight is to stay alive and grow, no sentience needed on the part of the tree. The fact that both oxygen and water vapor are released in the process is generally irrelevant to the survival of the tree.
This leads, however, to a situation where I think your stricter definition would apply; in a biodome such as Biosphere2
trees do have the purpose of creating oxygen from CO2
in the air. Knowing that something has a function and employing it for that function certainly gives the thing that function as a purpose, regardless of whether the function is there by design or not.
My point in making the above rant is that unless you don't understand my meaning in any of the sentences above, my use of the word "purpose" fits withing the scope of that word in the English language. Arguing that someone using it that way is wrong because their usage doesn't meet a stricter/narrower definition is misguided.
trpmb6 wrote:It truly is a multi-faceted topic. I just found myself flipping my opinion by using the argument that the leaf of a tree has purpose. I am at a loss really.
And I'm ninja'ed.
Feel free to ignore my rant entirely.