Scientists are people first, and people tend to find evidence for things they want to believe.

Moreover, the people who fund scientific research aren't even necessarily scientists, and they tend to give money to support accepted sets of assumptions. When Thomas Kuhn wrote The Structure of Scientific Revolutions, he was careful to distinguish between the single paradigm under which a field of science operates and the many options of belief open to practitioners of the humanities. Here's a famous passage, including a quote from Max Planck which is the basis for the old adage that science advances one funeral at a time:

Copernicanism made few converts for almost a century after Copernicus' death. Newton's work was not generally accepted, particularly on the Continent, for more than half a century after the Principia appeared. The difficulties of conversion have often been noted by the scientists themselves. Darwin, in a particularly perceptive passage at the end of his Origin Of Species, wrote: "Although I am fully convinced of the truth of the views given in this volume .. I, by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine. ..But I look with confidence to the future - to young and rising naturalists, who will be able to view both sides of the question with impartiality." And Max Planck, surveying his own career in his Scientific Autobiography, sadly remarked that "a new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.

While this goes well beyond the discussion of the Ivory Billed Woodpecker -- scientists don't need a whole separate paradigm in order to come to different conclusions about that, only different weighings of the evidence involved -- you have to wonder whether in this media- , politics-, and money-fueled age of scientific research whether paradigms are quite as solid as they used to be. There's almost something reassuring about a system where a whole generation of scientists have to die off before a new model can get a foothold.

Phil:

For a time I think there was too much resistance to the idea that the Ivory Billed Woodpecker could survive. Sure it is a big showy bird, but it's required habitat would naturally draw it to remote places.

On the other hand, once someone published - in the journal Science! - that it had survived, for many the debate was basically over before it began.

Either way it's counter-productive when ideology drives science.

Planck seems like another in a long and prodcutive line of humourless German scientists. I hope he's wrong- and getting wronger - about the necessity of a generational death being required.