I want to share with you something I read in an article by Nancy Krieger titled, Theories for Social Epidemiology in the 21st century: an eco-social perspective.  It is published in the International Journal of Epidemiology. 
(2002: 30:668-667).

I will just quote from the article and leave you to your own thoughts:
...the study of why some people swim well and others drown when tossed into a river displaces study of who is tossing whom into the current - and what else might be in the water. (p670)