What is the term for human beings' tendency to obey without thinking?
Obedience

The most famous paper dealing with this issue is Milgram's paper, called Behavioral study of obedience[1]. From the abstract:


  This article describes a procedure for the study of destructive obedience in the laboratory. It consists of ordering a naive subject to administer increasingly more severe punishment to a victim in the context of a learning experiment.




[1] Behavioral Study of obedience, Milgram, S. The Journal of Abnormal and Social Psychology, 1963. doi: 10.1037/h0040525 PDF link