"Because it's there," Mallory replied. Three words every mountaineer knows to be true, but an explanation that doesn't make any sense to those of us watching from the ground.

And throughout history, we've come up with ways to explain human behavior. 

"Psychology,"  \citet{Ebbinghaus1908} writes, "has a long past, yet its real history is short" (pg. 3). 110 years later, this quote is still at the beginning of most Psychology text books. And yet, much has happened in the field over the past century that has yet to filter into common consciousness. When people wonder, "why can't I motivate myself to workout?" or when companies ask, "why are we losing customers?" they often have no idea that there are academics who have spent whole careers figuring out the answers to these questions. Which really isn't the lay person's fault. If you're looking to Psychology for the Truth with a capital "T" for why people do what they do, you'll be disappointed. The last 100 years in field of psychology has undergone radical shifts, only to splinter, shift back, and splinter again. It's not uncommon for people to get PhDs researching a phenomenon and never even hear that there are a dozen models competing to explain that same phenomenon.  As \citet{Hergenhahn2013-yc} points out, "Psychology is not a place for people with a low tolerance for ambiguity" (pg. 625).