“Beware!” the professor warned, of the Single Factor Theory!

“What is that, and why should I care?”, I thought. 

That was in 1960. I was an 18 year old second year university student, to whom that warning seemed merely of academic interest.  I forgot all about it for the next 60 years, until it suddenly popped up in my memory. And now I understand it. Now I care.

Many – if not almost all – of the social, environmental and economic issues facing our societies have multiple, complex causes and effects.  Yet we instinctively reject complexity, looking for simple answers to complex questions.  Easiest of all is reducing the answer to a single factor.  The appeal of the single factor theory is that it reduces everything to a binary choice: the single cause either exists or it doesn’t.  Some current examples?