> But it's not like there's a natural force that ensures, compels, or mandates these rights.

A lot of really well regarded philosophers throughout the ages have disagreed with that.

> I guess my point is that taken less cynically, rights... only exist [with] sufficient power

If I follow that line of thinking, justice is only an extension of power. I don't think people agree with that.

I don't believe you think that. Perhaps it's just a matter of phrasing; surely we both agree that it's important to recognize that people should never murder people. We use the word "right" because it's important to be absolute in this rule.

It's worth distinguishing between:

  * life is not a right
  * we don't have enough power to enforce murder laws

...the second case is preferable, even if it may be hard to distinguish between the two looking down the barrel of a gun. If you believe in a deity, the could be justice in the afterlife. If you don't, one can be justified in history, if nothing else. For example, we don't say it was OK for Thomas Jefferson to own slaves because the U.S. didn't have the votes to ban the practice altogether. We say the slaves had their rights violated, not that they didn't deserve freedom and dignity because nobody could guarantee it.

tl;dr To say there are no absolute rights is to say there are no absolute wrongs.