Suppose you enter your Grandmother's house, hear a teapot whistling, and ask, "Why is the teapot whistling?" Someone could answer in terms of thermodynamics, fluid flow, the physical properties of water, acoustic properties of the nozzle on the kettle, etc. The answer would be a perfectly valid mechanistic answer of "why" the teapot is boiling. But someone could also answer that the teapot is boiling because Grandma is thirsty and wants her afternoon tea. This answer is just as valid and accurate as the first. One answer addresses mechanism, and the other addresses purpose.
So "how" is simply a level of explanation that requires less coarse-graining than a "why" explanation?
No matter how you decide to communicate it, the point is that science can only deal well with mechanistic, cause-effect explanations. It can't address teleological questions very well, if at all.
And how much evidence do we have that teleological explanations are ever required?
Thinking that "why" is something different to "how" (other than mere depth of observation) is begging the question. Stating that science cannot ascertain "purpose" is begging the question.
Until evidence is forthcoming, God, "purpose", and teleology are merely hypotheses, and I refer you to the comments made by our mutual predecessor, Laplace.
Edited by cavediver, : No reason given.