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October 2022  
  
If there were intelligent beings elsewhere in the universe, they'd share
certain truths in common with us. The truths of mathematics would be the same,
because they're true by definition. Ditto for the truths of physics; the mass
of a carbon atom would be the same on their planet. But I think we'd share
other truths with aliens besides the truths of math and physics, and that it
would be worthwhile to think about what these might be.  
  
For example, I think we'd share the principle that a controlled experiment
testing some hypothesis entitles us to have proportionally increased belief in
it. It seems fairly likely, too, that it would be true for aliens that one can
get better at something by practicing. We'd probably share Occam's razor.
There doesn't seem anything specifically human about any of these ideas.  
  
We can only guess, of course. We can't say for sure what forms intelligent
life might take. Nor is it my goal here to explore that question, interesting
though it is. The point of the idea of alien truth is not that it gives us a
way to speculate about what forms intelligent life might take, but that it
gives us a threshold, or more precisely a target, for truth. If you're trying
to find the most general truths short of those of math or physics, then
presumably they'll be those we'd share in common with other forms of
intelligent life.  
  
Alien truth will work best as a heuristic if we err on the side of generosity.
If an idea might plausibly be relevant to aliens, that's enough. Justice, for
example. I wouldn't want to bet that all intelligent beings would understand
the concept of justice, but I wouldn't want to bet against it either.  
  
The idea of alien truth is related to Erdos's idea of God's book. He used to
describe a particularly good proof as being in God's book, the implication
being (a) that a sufficiently good proof was more discovered than invented,
and (b) that its goodness would be universally recognized. If there's such a
thing as alien truth, then there's more in God's book than math.  
  
What should we call the search for alien truth? The obvious choice is
"philosophy." Whatever else philosophy includes, it should probably include
this. I'm fairly sure Aristotle would have thought so. One could even make the
case that the search for alien truth is, if not an accurate description _of_
philosophy, a good definition _for_ it. I.e. that it's what people who call
themselves philosophers should be doing, whether or not they currently are.
But I'm not wedded to that; doing it is what matters, not what we call it.  
  
We may one day have something like alien life among us in the form of AIs. And
that may in turn allow us to be precise about what truths an intelligent being
would have to share with us. We might find, for example, that it's impossible
to create something we'd consider intelligent that doesn't use Occam's razor.
We might one day even be able to prove that. But though this sort of research
would be very interesting, it's not necessary for our purposes, or even the
same field; the goal of philosophy, if we're going to call it that, would be
to see what ideas we come up with using alien truth as a target, not to say
precisely where the threshold of it is. Those two questions might one day
converge, but they'll converge from quite different directions, and till they
do, it would be too constraining to restrict ourselves to thinking only about
things we're certain would be alien truths. Especially since this will
probably be one of those areas where the best guesses turn out to be
surprisingly close to optimal. (Let's see if that one does.)  
  
Whatever we call it, the attempt to discover alien truths would be a
worthwhile undertaking. And curiously enough, that is itself probably an alien
truth.  
  
  
  
  
  
**Thanks** to Trevor Blackwell, Greg Brockman, Patrick Collison, Robert
Morris, and Michael Nielsen for reading drafts of this.  
  
  
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