Dogs believe that they are good. Soooooo true in so many ways, and God bless them for it.
These 'studies' are hysterical and layered with hidden gems for those of us who deal with studies ad nauseum. Thank you so much, @Pyrrhus, for sharing. (Your timing is also excellent, as I was just explaining this exact premise to others yesterday.)
On the Dungeons and dragons alignment Cats are chaotic evil, there is nothing of much you can teach them to follow any rules and they are entirely selfish.
Dogs are lawful neutral. They will mostly follow the rules you teach them mostly but you can teach them to be really evil or really good and they trend to be pretty flexible in which they are at any given moment.
I think the authors of the dog paper are severely biased and their research is in question! They state "dogs are arguably comparable to cats"! What nonsense is this? Dogs are unable to purr and thus demonstrably less good than cats.