Correct Cocentric Circles

I mentioned, in class, that there was moral merit in Singer's circles of moral preference and I thought that a blog would be a good opportunity to clarify and expound.

An initial, intuitive stance is that I care for my family more than I care for a dog in Denmark, a cat in Copenhagen. Johnson also mentioned that we do owe more moral consideration to humans than we do to non-human animals. If this precedent for preferential particularity is already set, than it follows that further stratification of selection is likely.

My contention is that, although the circles were posited as a negative attribute of contemporary morality, the circles accurately depict the moral landscape and there is merit to this. Steering, or rowing for that matter, away from a lifeboat example, a lack of moral differentiability can lead to some rather absurd circumstances in which one cannot decide between preserving the welfare of a family member as opposed to the welfare of a pet, a plant, a plate.

It is prudent, now, to note that possessing this preference does not neglect, is not exclusive, to a base level of respect that may be due all beings, but rather serves as a mechanism for categorizing one's responsibilities to the myriad of subjects that inhabit our world.

Question: Is there a moral mandate to care for all things equally, or can preference ethically exist?