I appreciate the accurate explanation, but it didn't seem to me to have much effect on the overall conclusion.
No, no, no. Principles matter, Mater. Two people can do the exact same action, materially speaking, but it could be a sin for one but a virtue for the other depending upon their formal intent, and it's the reasoning and principles applied that will determine the formal morality of the action. This is absolutely crucial and cannot be blown off as mere pedantic or academic splitting of hairs.
"Lesser evil" thinking is morally repugnant and must be repudiated by all Catholics. Period.
And there can in fact be radically different material outcomes of applying double effect vs. lesser evil.
So, no, it's absolutely NOT just hair-splitting.
Let us imagine a presidential election in which one candidate favors abortion but only in the first trimester while the other candidate wants no limits up to and including partial birth abortion. So can you vote for the first-trimester abortion proponent as a "lesser evil"?