Saturday, March 3, 2012

Animal consciousness

Sometimes I come up with an argument such that I can't tell for sure if it's more a joke or a really interesting argument. The following is a case in point:

  1. (Premise) If some non-human earthly animals are conscious, all normal mammals are conscious.
  2. (Premise) There have ever been several orders of magnitude more non-human mammals than humans.
  3. (Premise, plausibly a consequence of 2) If all normal mammals are conscious, I should very strongly expect not to experience reality as a human.
  4. (Premise) I experience reality as a human.
  5. So, probably, not all normal mammals are conscious. (By 3 and 4)
  6. So, probably, no non-human earthly animals are conscious.
As for (1), if some non-human earthly animals are conscious, a line must be drawn as to where consciousness is found. There are two main plausible places to draw such a line: (a) humans versus other animals, and (b) animals with sophisticated brains versus other animals. If we draw the line in the second place, all normal mammals will be conscious. As for (2), I don't have data as to how many mammals there are on earth. I saw an unreferenced "400 million" online, and a referenced somewhat smaller estimate for the number of birds (and I could run the argument with birds, too, I think). There are apparently roughly as many rats and mice in the world as humans. And there have been non-human animals for millions of years before there were humans.

I think the difficult philosophical question is whether (3) is true and what sense can be made of it.

I am more inclined to see this argument as a joke, or maybe as a challenge to figure out how anthropic arguments work.

7 comments:

Mike Almeida said...
This comment has been removed by the author.
Mike Almeida said...

If all normal mammals are conscious, I should very strongly expect not to experience reality as a human.

That premise should rather be,

If all normal mammals are conscious, and i didn't know I was a human, I should very strongly expect not to experience reality as a human.

CorkyAgain said...

The inference from 3 to 4 seems fallacious.

The fact that I do in fact have a human consciousness might be a rare and unusual event in the grand scheme of things, something that defies all expectation.

But the existence of the rare and unusual is not in itself an argument against the more common occurrences.

CorkyAgain said...

Sorry, I meant the inference from 3 and 4 to 5.

Alexander R Pruss said...

CorkyAgain:

If we have two serious incompatible (relative to the background) hypotheses, H1 and H2, and an observed event E that is rare and unusual on H1 but quite likely on H2, then E favors H2 over H1.

Let H2 be: only humans are conscious.
Let H1 be: all (normal) mammals are conscious.

Mike:

Isn't this just a case of the problem of old evidence?

Jonathan Livengood said...

If we have two serious incompatible (relative to the background) hypotheses, H1 and H2, and an observed event E that is rare and unusual on H1 but quite likely on H2, then E favors H2 over H1.

Let H2 be: only humans are conscious.
Let H1 be: all (normal) mammals are conscious.


What exactly is the evidence? Suppose that E is: I am conscious. There are now, I think, two readings.

Reading 1: The fact that I am human may be assumed as background knowledge. Then the evidence is entailed by both hypotheses: P(E|H1,B) = P(E|H2,B) = 1. So, E doesn't favor either hypothesis.

Reading 2: The fact that I am human may not be assumed as background knowledge. Then on H1, the probability that I am conscious reduces to the probability that I am an animal: P(E|H1) = P(A), where A is "I am an animal." And on H2, the probability that I am conscious reduces to the probability that I am human: P(E|H2) = P(M), where M is "I am a human." But since there are non-human animals, P(A) > P(M), and hence, P(E|H1) > P(E|H2). So, on the second reading, the evidence favors the hypothesis that all animals are conscious. It does an even better job of supporting the hypothesis that everything is conscious!

Alexander R Pruss said...

Jonathan:

From the original post, it looks like E = "I experience reality as a human."

That I am conscious does go into the background here.

Your comments do point to a deeper worry, though. Why not take that I am conscious to be (old) evidence as well, and conclude that panpsychism is true? Or, worse, why not conclude that probably Berkeley's idealism is true, by taking as evidence that I experience reality as a human, and noting that unless idealism is true, it is unlikely that I would do so, since most unless idealism is true, the vast majority of entities in the world (bacteria, photons, etc.) do not experience reality as a human?

Move 1: The prior on idealism is very small but non-zero and the correct fundamental physics is based on fields, not particles. Consequently, while the fact that I am conscious does increase the probability of idealism, the probability of idealism stays small. Why did I have to assume that the correct physics is based on fields? Well, if it's based on particles, then there'll be around 10^80 of them in the world, and if idealism is false, there will be only a handful of conscious beings in the world (say, 10^20), and so P(I am conscious | no idealism and 10^80 particles) is 10^-60.

Move 2: Theism has probability 1, and idealism has probability 0 given how we experience the world and given theism, since God couldn't allow us to be deceived. I actually like this option a fair amount.

Move 3: When considering the possibilities for how I might have experienced reality in arguments like this, I should count other conscious beings but not other unconscious beings. It may be hard to defend this move.

Move 4: All arguments of this sort--Doomsday, the animal argument, the idealism argument--are flawed. One reason might be because they presuppose the assignment of non-zero epistemic probabilities to propositions that are in fact are metaphysically impossible, such as that I be a particle or I be a non-human animal. If this is right, then one can't use probabilistic reasoning in such self-locating cases. This could have implications for Sleeping Beauty, too, since sentences like "It is now Monday" express metaphysically necessary truths when they are true, since "now" refers rigidly.