Source: Dr. Barry Bickmore, Professor of Geologic sciences at Brigham Young University, lecture on You Tube, "How to Avoid the Truth about Climate Change."
Notes: Famous dissentors of climate change, such as Texas Governor Rick Perry, like to dissmss the overwhelming scientific agreement on climate change stating that "even Galileo got outvoted for a spell."
In 1633, the Catholic Church unfairly convicted Galileo of heresy for his statements supporting heliocentrism, the idea that the earth revolves around the sun, which contradicted the church's teaching that the earth was the center of the universe. Today, Galileo is considered to be a hero, especially among climate contrarians for prompting that idea in the face of strong fight from the Catholic church.
Oddly, Galileo had a weak primary argument to support his theory. He proposed ocean tides were the strongest evidence to support his theory. Galileo was convinced the earth revolved around the sun because the tides showed that the ocean water sloshed back and forth. Galieo used the twice-daily incoming and outgoing Mediterranean tides to demonstrate his theory, and calculated that tides occurred only once a day for the Atlantic. This, of course, was an error. The more people told Galileo he as wrong, the more he dug in his heels. He never rejected his argument. Only later were tides shown to result from the gravitational pull of the moon, and compelling evidence for this forged a new scientific consensus.
The point, according to Dr. Bickmore, is that even great scientists can behave dogmatically. Therefore, scientific consensus is crucial. "People who say science is not about consensus, they do not understand science."
Dr. Bickmore went on to say that
"We have always had (scientific) loners out there. The brilliant loners who come up with some great idea. The problem is that they are often not perfect ideas. It did not pick up any legs because it did not have what the modern scientific community has, which is the community itself. Whenever a scientist presents an idea that is not perfect, there is going to be dozens of other scientists beating the crap out of it for an extended period. They do this to work out all the kinks to make it better than before. That is the difference the Greek philosophers and modern science: consensus."
update 5-26-12 TS -- For a point-by-point rebuttal of the Galileo argument used by 'skeptics,' see Modern Scientists Follow in Galileo's Footsteps by Tom Smerling, on Skeptical Science. Also "Galileo Gambit" on RationalWiki.