It has degrees; it isn't absolute. If I see my neighbor Smith's dog get
loose and attack my neighbor Jones's cat, I'll try to stop the attack
and save Jones's cat. If I see Smith's dog attack a squirrel in the
front yard, I probably won't try to save the squirrel; if I do try to
stop the attack, it will be more out of consideration for Smith and how
he wants his dog to behave. If I see a coyote come down the street and
attack the squirrel, for certain I won't do anything to try to save the
squirrel.

The squirrel simply doesn't enter into my imprecise calculus of moral
consideration in the same way that Jones's cat does, and to the extent
it enters into it at all, it's highly context-dependent. No one gives
equal moral consideration to the interests of all beings capable of
suffering, nor should we be expected to do so. We may not be able to
say exactly where we draw lines, but that doesn't mean it's arbitrary.
In any case, the "ar" radicals tell us that arbitrariness sometimes
doesn't matter, or sometimes it does, so they are being arbitrary.

For example, I am told that it is permissible for me to take my kinship
with my child into account in deciding whether to rescue him or some
other child from an impending catastrophe where I have time to rescue
only one of them. However, the same source would tell me that if
neither of the two children were my known relatives, but if one were of
my race and the other were of a different race, I would not be able to
use race - also an indication of kinship, even if much more remotely so
than family - in deciding which one to rescue.

The sophists are trying somehow, any way they can, to find a means to
salvage something they intuitively like. There is no rigor to it at all.