The credible bluff is in relation to the realization that a “bluff” in poker is not actually a real thing in the general way society perceives it. This lays down the understanding for something that might seem to contrast such a realization: The credible Bluff.
A bluff cannot be effective if it is not at all credible, thus we say for a bluff to have value it must be credible.
Furthermore, a bluff by nature must not be that which it represents. In other words if we wish to bluff a certain board in poker, we cannot hold the nuts (the best possible hand), otherwise how can it be said to be a bluff?
Our villain cannot be expected (at least to some probabilistic extent) to have a worse hand than ours, otherwise we cannot really full fill the previous requirements.
But then again we seem to have two conflicting rules here. On the one hand we must have the worst of the hands to truly be bluffing, but on the other hand in order for it to be “credible” there must be some plausibility that we will “go through” with our bluff.
For example we might bet or raise vs a villain as a bluff, and if villain re raises we therefore cannot call with our worse hands. This example and writing are skewed of course because of the different religious understandings players have on what poker is.
In the this perspective, it is the author’s belief and want for the levation, of the credible bluff, in the form that we raise with the obvious intention of calling villains re raise with a weaker hand.
That is the hero is willing to burn some equity in a vacuum for a vastly superior result not understood to the villain. The villain then cannot re-bluff, but must address the situation as is.