Thanks for the reply.

If we change the story as you describe I guess the moral of the story would probably become "investigate thoroughly". Obviously Bayesians are never really certain - but deliberate manipulation of one's own map of probabilities is unwise unless there is an overwhelmingly good reason (your hypothetical would probably be one - but I believe in real life we rarely run into that species of situation).

The story itself is not the argument, but an illustration of it - it is "a calculation of the instrumentality of various options ought to include a generalised weighting of the truth (resistence to self-deception) because of the consequences of self-deception tend to be hidden and negative". I additionally feel that this weighting is neglected when the focus in on "winning". I can't prove the emprical part of the first claim, because its based on general life experience, but I don't feel its going to be challenged by any reasonable person (does anyone here think self-deception doesn't generally lead to unseen, negative consequences?).

I don't feel confident precribing a specific formula to quantify that weighting at this time. I'm merely suggesting the weight should be something, and be significant in most situations.