A Calculus of Purpose

  title={A Calculus of Purpose},
  author={Arthur D. Lander},
  journal={PLoS Biology},
  pages={168 - 171}
W hy is the sky blue? Any scientist will answer this question with a statement of mechanism: Atmospheric gas scatters some wavelengths of light more than others. To answer with a statement of purpose—e.g., to say the sky is blue in order to make people happy—would not cross the scientifi c mind. Yet in biology we often pose " why " questions in which it is purpose, not mechanism, that interests us. The question " Why does the eye have a lens? " most often calls for the answer that the lens is… CONTINUE READING