A google search for "handgun stopping power" (without the quotes) reports "About 7,060,000 results". A google site search (site:castboolits.gunloads.com handgun stopping power) shows that about 800 of those results are from castboolits.
In those 7 million internet pages (or even just in the 800 pages from this forum) there must be a lot of different opinions about "handgun stopping power." My own opinion is that the FBI probably got it right in 1989 when Special Agent Urey Patrick wrote "The critical wounding components for handgun ammunition, in order of importance, are penetration and permanent cavity."
But that was some time ago. I'm curious not just about the current thinking, but also about the history of the idea. What theories have been proposed? What theories have been rejected and why? And what theories have been generally accepted? Any thoughts?