A comment by Kristor from:
In which he explains why things that are similar are in fact, and necessarily, different in their essence.
Dogs clearly take some responsibility.
My dog Rosie is capable of lying, and of shame at the way she has behaved. Otherwise, the utterance, “Bad dog!” would have zero meaning to her, or therefore to me. It would mean nothing intelligibly different than “Good dog!” or “Squirrel!”
And, meaning nothing different to Rosie, none of these utterances of mine would affect her differently. But they do. She responds appropriately to my utterances, if not intelligently.
But this is very far from saying that she is equal in dignity to me.
For, because I can comprehend my actions vis-a-vis the world far more completely than she, so I can take a more informed responsibility for my actions.
The more comprehensive the information of my actions, the more efficacious they are, and the greater my dignity (and my liberty).
My dignity as a man, then, as different quantitatively from hers, is ipso facto different qualitatively, in just the same way that possessing $10 is qualitatively different from possessing $1,000,000.
The bottom line: a quantitative difference just is a qualitative difference; for quantity is a quality.
Where the quantitative difference is trivial, it is negligible; where not, not.
It all comes down to a judgement of importance. The difference of intelligence between me and Rosie puts us in different categories of things, just as the difference of mass between Jupiter and Sol puts them in different categories.
Categories are porous, to be sure, so that taxonomies are bound upon close examination to look somewhat adventitious, in one way or another; but if categories were not real, there would be no membrane to have the pores, no way to arrive at the conclusion that the boundaries are somewhat arbitrary.
You can’t say that things are close to each other, or similar, without implicitly admitting that they are truly and fundamentally and essentially different.
Again, it all comes down to a judgement about how important those differences are.