There are a couple of lines of thought with this argument. The first would be that Japan's attitude coming out of the demands made at the Potsdam Conference was so rooted in defiance that no amount of prior knowledge would have helped. When Truman emerges from the Potsdam Conference and details the "destruction" that will be visited upon Japan without a surrender, the Japanese response is to ignore it, or to engage in "yakinaoshi," meaning to "kill by silence." In this, the Japanese reaction was so steadfast against the West that little, if anything, would have persuaded them to recognize what was to come.
Yet, it is precisely this logic where some argue that Japan might have relented. Truman never discloses that he intended to use nuclear weapons, a reality that could have persuaded the Japanese to surrender or at least recognize the implications of their defiance. It is here where I think that some who argue that full disclosure would have prompted Japanese surrender might have a point to make. Had Japan realized what was going to be done, there might have been a response a bit more substantive than the political bluster of diplomats during wartime. In the end, one has to weigh out both opinions. I think that there was a definite element of resistance on the part of the Japanese, something that would not have changed until the use of nuclear weapons was felt with total and absolute certainty.