I'm searching for three good definitions of technology in the economics  
   literature, preferably by prominent economists: (a) one that matches the  
   standard  textbook  approach that technology represents the production  
   possibilities of factor substitution; (b) one that, in this way, sees nature  
   as imposing technological constraints on production; and (c) one that sees  
   technological progress as an augmentation of factor  sustitution  
   possibilities (as popularised by Solow, etc.).  
  
   Even better would be if someone could point me towards the origins of any of  
   these three (related) ideas.  
  
   Many thanks in advance  
  
   Adam McHugh