Minor spoilers for HPMOR, I guess?

SUMMARY

Sometimes, if you do something, people will call it good.  Other times, if you do something, people will call it bad.

These words actually cover two different kinds of moral judgment: judgment of actions and judgment of character.

Judgment of actions is evaluating whether these actions are good or bad actions - whether they lead to good or bad consequences.  For example, murdering someone is bad because it results in that person being murdered.

Judgment of character is evaluating this action as Bayesian evidence of your character - whether it says good or bad things about the other actions you are likely to take.

Sometimes these two things align: murder is bad on both forms of judgment.

However, confusion can arise when these two forms of judgment lead to different answers.  In cases like this, it's valuable to distinguish which kind of judgment you're using, and to understand that these two forms are not necessarily consistent with one another.

THE GUY WITH THE FLAMING SKULL TATTOO

Suppose that Bob gets a large tattoo of a flaming skull on some visible part of his anatomy.

By judgment of actions, it's hard to argue that this act has any particular moral impact.

But by judgment of character, this tattoo serves as a reasonable quantity of Bayesian evidence of bad character.  If you see Bob having such a tattoo, you can correctly conclude that Bob is more likely to be violent, more likely to commit crimes, etc.

These two forms of judgment are in tension.  Judgment of character suggests that, when you see Bob's tattoo, you should judge him as more likely to be a bad person - that you should be less likely to trust him, less likely to hire him to babysit your children, less willing to meet him in an abandoned parking lot to buy the PS5 he advertised on Craigslist, etc.  But judgment of actions declares that Bob has not actually harmed anyone, and there's no reason to punish him.

One resolution to this tension is to distinguish between social and legal punishment.  We are often willing to apply social punishment based on judgment of bad character (most people would not disapprove of you for refusing to meet Bob somewhere that isn't public), but not willing to apply legal punishment (most people would disapprove of the police arresting Bob on a charge of 'having a tattoo that we think is Bayesian evidence of wrongdoing').  

EVIL AND LOYALTY

In Ch54 of HPMOR, Harry discovers that Bellatrix Black is incredibly loyal to the Dark Lord, and that the Dark Lord does not appreciate this loyalty and abuses her anyway:

If someone shows me that much loyalty, even by mistake, there's a part of me that can't help but feel something. The Dark Lord must have been... evil doesn't seem like a strong enough word, he must have been empty... to not appreciate her loyalty, artificial or not.

This makes very little sense from the standpoint of judgment of consequences.  Failing to adequately appreciate his minion's loyalty is not a noticeable increase to the amount of evil the Dark Lord has done, compared to the huge amount of murders and torture we already know he is responsible for.

But it makes a fair amount of sense from the standpoint of judgment of character.  Many very evil people, who have done a great deal of harm, have been honorable, loyal towards their loyal subordinates, etc.  Learning that the Dark Lord mistreats even his most loyal servant is further evidence of his bad character and irredeemable nature, even if it's not the worst thing he did.

WHY NOT EAT YOUR PET DOG?

“Well, there was a bit of a fracas, as we say, and it turned out that a man had a dog, a half-dead thing, according to bystanders, and he was trying to get it to stop pulling at its leash, and when it growled at him he grabbed an axe from the butcher’s stall beside him, threw the dog to the ground and cut off its back legs, just like that. I suppose people would say ‘Nasty bugger, but it was his dog’ and so on, but Lord Vetinari called me in and he said to me, ‘A man who would do something like that to a dog is a man to whom the law should pay close attention. Search his house immediately.’ The man was hanged a week later, not for the dog, although for my part I wouldn’t have shed a tear if he had been, but for what we found in his cellar. The contents of which I will not burden you with.

Terry Pratchett, Snuff

One common argument for vegetarianism goes something like this:

You say that factory farming of pigs is okay, because they are 'non-sapient' or in some sense stupid enough it's fine to eat them.  But pigs are if anything somewhat more intelligent than dogs, and you support laws against animal cruelty towards pet dogs.  

If you actually had a consistent policy that animals had no moral value, you would think that dogfighting rings, or even just killing your dog for your own amusement, would be perfectly legal - you can't find a weight to place on animal welfare that forbids abusing your pet dog but allows factory farming of pigs.  

Your actual moral policy seems to be something like 'dogs are cute, pigs are not', but this is obviously not a good way to make a decision.

This article explains what I think is a large part of my response to this.  

Abusing your pet dog is objectively not very harmful in terms of [amount of harm done] & [level of sapience of victim], much less harmful than e.g. factory farms.  

However, abusing your pet dog is extraordinarily strong evidence of bad character.  If you respond to the level of loyalty that almost every dog shows you with abuse, I think there is something deeply and profoundly wrong with you and I want you removed from society as soon as possible lest whatever-it-is manages to spread.   This is perhaps not entirely fair - as in the tattoo example above it is strange to want to impose legal punishment based on evidence of bad character - but I have a hard time finding it in me to disagree with it.