> But "function" only exists for something that was created by intellectual being with a goal in mind. That doesn't bother me, since I think it's pretty obviou

> But "function" only exists for something that was created by intellectual being with a goal in mind. That doesn't bother me, since I think it's pretty obvious that there must be a prime mover of some sort. > How can you define "function" for something that evolved naturally? What it does. A kidney filters blood (and performs some other functions as well): a kidney which doesn't filter blood is obviously unhealthy. A heart pumps blood: a heart which fails to pump blood is obviously unhealthy. Gonads produce reproductive cells and introduce them to sexual partners: a set of gonads which don't produce such cells, or fail to introduce them to sexual partners, is obviously unhealthy. At a higher level, an organism is a mechanism for propagating genes. An organism which propagates its genes fulfills its function; one which does not fails to fulfill its function (note that ensuring the propagation of one's relatives' similar genes can count as a partial fulfillment at least).