Perhaps the fact that we are so confused by anthropic reasoning is a priori evidence that we are a very early anthropic reasoners and thus the Doomsday argument is false. Further, not every human is an anthropic reasoner. If the growth rate of anthropic reasoners is less than the growth rate of humans we should then extend the estimation of the lifespan of a human race with anthropic reasoners (and of course this says nothing about the lifespan of humanity without anthropic reasoners).
A handful of powerful anthropic reasoners could enforce a ban on anthropic reasoning: burning books, prohibiting it's teaching and silencing those who came to be anthropic reasoners on their own. If within two generations we could stabilize the anthropic reasoner population at around 35 (say 10 enforcing, 25 to account for enforcement failure) with life spans averaging 100 years that would put us in the final 95% (I think, anyone have an educated estimate of how many anthropic reasoners there have been up to this point in time?) until a permanent solution was reached or humanity began spreading and we would need at least one enforcer for every colony-- but given optimistic longevity scenarios we could still keep the anthropic reasoner population to a minimum. The permanent solution is probably obvious: A singleton could enforce the ban by itself and make itself the last or at least close to last anthropic reasoner in the galaxy.
The above strikes me as obviously insane so there has to be a mistake somewhere, right?
Maybe somebody will just come up with an elegant explanation of the underlying probability theory some time in the next few years, it'll go viral among the sorts of people who would otherwise have attempted anthropic reasoning, and the whole thing will go the way of geocentrism, but with fewer religiously-motivated defenders.
...at least not if you accept a certain line of anthropic argument.
Thomas Nagel famously challenged the philosophical world to come to terms with qualia in his essay "What is it Like to Be a Bat?". Bats, with sensory systems so completely different from those of humans, must have exotic bat qualia that we could never imagine. Even if we deduce all the physical principles behind echolocation, even if we could specify the movement of every atom in a bat's senses and nervous system that represents its knowledge of where an echolocated insect is, we still have no idea what it's like to feel a subjective echolocation quale.
Anthropic reasoning is the idea that you can reason conditioning on your own existence. For example, the Doomsday Argument says that you would be more likely to exist in the present day if the overall number of future humans was medium-sized instead of humongous, therefore since you exist in the present day, there must be only a medium-sized number of future humans, and the apocalypse must be nigh, for values of nigh equal to "within a few hundred years or so".
The Buddhists have a parable to motivate young seekers after enlightenment. They say - there are zillions upon zillions of insects, trillions upon trillions of lesser animals, and only a relative handful of human beings. For a reincarnating soul to be born as a human being, then, is a rare and precious gift, and an opportunity that should be seized with great enthusiasm, as it will be endless eons before it comes around again.
Whatever one thinks of reincarnation, the parable raises an interesting point. Considering the vast number of non-human animals compared to humans, the probability of being a human is vanishingly low. Therefore, chances are that if I could be an animal, I would be. This makes a strong anthropic argument that it is impossible for me to be an animal.
The phrase "for me to be an animal" may sound nonsensical, but "why am I me, rather than an animal?" is not obviously sillier than "why am I me, rather than a person from the far future?". If the doomsday argument is sufficient to prove that some catastrophe is preventing me from being one of a trillion spacefaring citizens of the colonized galaxy, this argument hints that something is preventing me from being one of a trillion bats or birds or insects.
And this could be that animals lack subjective experience. This would explain quite nicely why I'm not an animal: because you can't be an animal, any more than you can be a toaster. So Thomas Nagel can stop worrying about what it's like to be a bat, and the rest of us can eat veal and foie gras guilt-free.
But before we break out the dolphin sausages - this is a pretty weird conclusion. It suggests there's a qualitative and discontinuous difference between the nervous system of other beings and our own, not just in what capacities they have but in the way they cause experience. It should make dualists a little bit happier and materialists a little bit more confused (though it's far from knockout proof of either).
The most significant objection I can think of is that it is significant not that we are beings with experiences, but that we know we are beings with experiences and can self-identify as conscious - a distinction that applies only to humans and maybe to some species like apes and dolphins who are rare enough not to throw off the numbers. But why can't we use the reference class of conscious beings if we want to? One might as well consider it significant only that we are beings who make anthropic arguments, and imagine there will be no Doomsday but that anthropic reasoning will fall out of favor in a few decades.
But I still don't fully accept this argument, and I'd be pretty happy if someone could find a more substantial flaw in it.