There is a study out that reports to show that dogs have a "sense of fairness". (See, Associated Press:Studies Show Dogs Have Sense Of Fairness)
Since I deny that a sense of fairness exists, I naturally have some objections to the claim that a particular study shows that dogs have that which does not exist.
I object to moral sense theories in general. Moral sense theories are theories that say that moral properties exist "out there" in the universe, and that we have a moral sense organ that allows us to detect these properties. In much the same way that our eyes see trees and cars, our "moral sense" sees fairness and unfairness – a theory that says that fairness and unfairness exists "out there" in the same way that trees and cars do.
The problem with moral sense theories is that we do not sense moral properties. We only sense our own likes and dislikes. Of course, it is tempting for us to view our likes and dislikes to be "moral properties" that exists "out there".
That interpretation then gives us a justification for forcing others to act in way that fulfill those particular desires. "I am not forcing you to do X merely because I like some result. I am forcing you to do X because it realizes something that (I sense) to hold a moral property that makes it worthy of being promoted, even if I did not want to promote it."
It’s like the argument, "I'm not condemning you for your homosexuality. God is. I am simply following God’s will." In fact, God has no will. God has no morality other than that which the theist assigns to God. So it is not "God's will" the theist is enforcing – it is his own prejudices.
So, a study that claims that dogs have a "sense of fairness" is as objectionable as saying that dogs have the capacity to sense God’s presence. In fact, why not use this explanation? What the dogs are sensing is not "fairness" but "God's will." Recognizing God's disapproval, and having an innate disposition (provided by God) not to do things that God disapproves of, they avoid that which we call "unfair". That is why the researchers got the results they did.
Ask the researchers why it is that the "sense of fairness" theory is better than the "God's approval" theory. The only difference between the two theories is the assumption that "fairness" exists as an entity to be sensed and that we (including dogs) have an organ capable of sensing it, versus the assumption that God's approval exists as an entity to be sensed and that we (including dogs) have a capacity for sensing it.
Both options represent equally good "science".
I would like to add that I am a moral realist – I think that moral properties do exist. I simply deny that that both divine command theories and moral sense theories are mistaken about what moral properties are. The entities those theories refer to do not exist. Clearly, other alternatives are available.