The article Contingencies over B. F. Skinner’s Discovery of Contingencies by Dr. Julie S. Vargas is now available on the B. F. Skinner Foundation’s website. Originally this article appeared in EUROPEAN JOURNAL OF BEHAVIOR ANALYSIS in No. 2, Winter 2004.

B. F. Skinner began graduate school thinking he would extend Pavlov and Watson’s stimulus-response
analysis of behavior. He met the physiologist William Crozier who encouraged Skinner’s inductive approach.
With little supervision and a willingness to build new equipment and start over, Skinner’s work
was determined largely by the data he was getting. Bit by bit those data shaped the operant chamber that
allowed Skinner to discover that postcedents, not antecedents determined what his rats did. Thus began a
new science. The science eliminates the role of hypothesized inner agencies and instead relates properties
of behavior directly to contingent events.

You can read the article here.