I assume it's a trick coin before the first toss because that's how I roll.
I'll just quote Yudkowsky:
And when you ask these strange beings why they keep using priors that never seem to work in real life... they reply, "Because it's never worked for us before!"
Now, one lesson you might derive from this, is "Don't be born with a stupid prior." This is an amazingly helpful principle on many real-world problems, but I doubt it will satisfy philosophers.
Everything I've seen needs rearranging And for anyone who thinks it's strange Then you should be the first to want to make this change And for everyone who thinks that life is just a game Do you like the part you're playing? -- Love (Arthur Lee) - "You Set the Scene"