Climategate: 'The Copenhagen Diagnosis' Fails Logic 101
Skeptics will be pleased that critical studies of proxy reconstructions are cited (Soon & Baliunas and McIntyre & McKitrick), but they're there only to show how open-minded the "Diagnosis" authors can be. For no sooner do they admit these criticisms, then do they immediately claim that these papers "have been rejected in subsequent work."
Rejected is not, of course, the same as refuted, but who would notice a nice logical point like that?
But even if these criticisms were refuted, the subsequent "hockey sticks" and other pictures of historical changes in temperatures are not direct proof for AGW's validity. The "Diagnosis" authors, it is obvious, do not understand this. They feel that because it might have been colder in the past, and warmer now, that this proves AGW. It simply does not.
Those observations are consistent with many theories of climate change, AGW being just one of them. What would be proof, and what is missing from the "Diagnosis," is evidence that the AGW models have skillfully predicted future temperatures.
They have not done so.
In fact, to disguise the AGW models' poor performance, they employ statistical slight of hand: every picture of temperature leaves out the last few years of cooling. This is because AGW models said it would grow hot, but we actually cooled.
The models, in other words, were wrong.
Lest our dear leaders notice this and become confused, the "Diagnosis" authors resort to the oldest logical fallacy. They simply assert: "We are smart people, therefore AGW is true."
Unfortunately, and since people are so willing to believe, that might be all the proof that is needed.