Every large, unselective group includes some villains.  Say whatever you like about the average moral caliber of Christians, atheists, Democrats, Republicans, plumbers, comic book fans, or Albanians.  The fact remains that each of these groups contains some awful people.  While this isn’t logically necessary, it is an iron statistical law.  If X has more than a few dozen members, and you can join group X by (a) being born into X, or (b) saying “I’m an X,” then X will have some unsavory characters.

When you identify with a large, unselective group, you expose yourself to two dangers.  First, some of the villains in your group may take villainous actions that make you look bad.  Yet on reflection, that’s a minor concern: Yes, the bad members of your group make you look bad, but the good members of your group make you look good. 

The second danger is more severe.  Once you identify with any large, unselective group, you will be regularly tempted to commit the villainous act of standing up for your groups’ villains.  When they do wrong – as they inevitably will – your impulse will be to ignore, minimize, or justify their misdeeds.  To quote the underrated 8mm, “If you dance with the devil, the devil don’t change. The devil changes you.”

Look at any large, unselective group you don’t identify with.  You see them clearly, do you not?  Some of its members are plainly bad people.  But getting the regular members to unequivocally condemn their bad members is almost impossible.  Evolution has honed their myside bias for millions of years, and that’s not about to change.

Fortunately, there are relatively easy ways to avoid these temptations in the first place – to save yourself from all shameful identities.  Namely: Never identify with large, unselective groups!  Instead, restrict your identity to groups that are small, selective, or both.

The nuclear family is the classic small, unselective group; no other group is more deeply founded in human nature.  Fortunately, the moral risk of being part of such a family is usually small.  Even if you have five kids, there a good chance that none of them will be horrendous people.  Circles of friends are the classic small, selective group.  Pick your friends carefully, and you probably won’t end up an apologist for evil.

Large, selective groups are riskier.  In principle, they can evade statistical villainy by carefully vetting and excommunicating questionable members.  Unfortunately, myside bias tends to gut the excommunication process.  Fringe movements like Jehovah’s Witnesses expel members all the time, but not the Catholic Church. 

The best way to guard against this laxity is to define your large, selective groups in purely intellectual terms.  Identify with liberalism or conservatism, not liberals or conservatives.  This is the kernel of truth behind the “No True Scotsman” fallacy.  Once you insist that “No true libertarian believes in immigration restrictions,” you’ll feel little temptation to ignore, minimize, or justify libertarians who believe in immigration restrictions.  And this is precisely how you should feel. 

Can anyone really live up to my puritanical advice?  Yes.  Take me.  I identify with my nuclear family, with my friends, and with a bunch of ideas.  I neither need nor want any broader identity.  I was born in America to a Democratic Catholic mother and a Republican Jewish father, but none of these facts define me.  When Americans, Democrats, Republicans, Catholics, and Jews commit misdeeds – as they regularly do – I feel no shame and offer no excuses.  Why?  Because I’m not with them.