Over the last month or so, Bryan Caplan, professor of economics at George Mason University, and Michael Huemer, professor of philosophy at the University of Colorado, Boulder, have engaged in a back and forth on the nuances of animal rights, specifically the rights of insects.
Ultimately, the crux of the debate rests on where to place the fundamentally arbitrary line of granting certain rights to pain-sensing organisms. As Caplan discussed in the first installment that got this debate started, even PETA and other animal rights advocates are unclear on what distinguishes insects from the rest of the animal kingdom. According to PETA:

All animals have feelings and have a right to live free from unnecessary suffering–regardless of whether they are considered “pests” or “ugly.””]

As with our dealings with our fellow humans, the determination of when lethal defense against insects and animals is acceptable must be judged on a case-by-case basis, taking into account the level of the threat and the alternatives that are available. As Albert Schweitzer once said “Each of us must live daily from judgment to judgment, deciding each case as it arises as wisely and mercifully as we can.””]
To this, Caplan responds:

A bizarre juxtaposition. No one would say that humans have a “right to live free from unnecessary suffering,” then immediately talk about killing them on a “case-by-case basis.”  And if someone killed hundreds of humans with his car on a cross-country trip, no one would accept the excuse, “It was necessary to cross the country.” If your only mode of transportation kills innocent human beings, you’re obliged to stay put. General principles notwithstanding, PETA clearly smuggles in the common-sense intuition that human lives are more morally important than insect lives. Indeed, it smuggles in the assumption that human convenience is more morally important than insects’ very lives.”]
All of this is to say that Caplan’s primary argument here is that even if some of the most ardent believers of animal rights make concessions with respect to the rights of insects, then that could be an indication that PETA and other animal rights activists are hypocritical, or at least not applying their first principles equally across the board.
Enters Michael Huemer, who begins his response with the following:

I don’t think the best way of determining whether x is true is by seeing whether x-advocates are hypocritical or morally flawed….
Rather, the best way to find out whether x is true is to just look at the arguments for and against x, especially if those arguments are simple and easy to find.”]
To Huemer, it matters not that animal rights advocates might be hypocrites. What matters is the actual arguments for and against extending rights to non-humans. He continues:

The arguments on ethical vegetarianism are simple and easily found. It seems wrong to cause extreme amounts of pain and suffering for the sake of minor benefits to oneself. If you just look at some of the things that go on on factory farms, you’re going to be horrified. If you look, I think you are going to find it extremely difficult to say, “Oh yeah, that seems fine.”
…
Maybe the suggestion is that it’s self-evident that pain is only bad if you’re smart. But then, rather than trying to draw inferences about this by looking at the behavior of PETA-members, etc., it seems like we could just introspect and see whether that’s self-evident. When I do, I see that it’s not self-evident (indeed, it isn’t even plausible). I don’t have to make any inferences or look at anyone else’s behavior, since I can just look and see.”]
You can read their debate in its entirety over at Econlog (Part 1, 2, 3 and 4). What do you think? At what point is it appropriate to concede that harming an animal is a violation of its rights? Is it the existence of a central nervous system? If it’s okay to kill insects, is it also okay to kill pigs and cows? Let us know what you think in the comments.