A follow-up posting by me: Cold fusion is not unique. There are many, many examples of previous claims that were rejected even though the proof was rock solid, and there was no reason to doubt the claims. Lasers, the MRI and h. pylori are good examples. I have studied much of this history, digging up old books and contemporaneous original sources. People don't like to talk about these events so you seldom see them in history textbooks.
I think there are many causes. As I said, it is human nature. Another major contributing factor is money. M-o-n-e-y, especially research funding. The locus of opposition to cold fusion has been the hot fusion program researchers, for obvious reasons. You see this in other institutions. The coal industry is fighting tooth and nail against natural gas and wind power. The congressman from Big Coal (WV) tried to pass a law banning the use of wind turbines, ostensibly because they kill birds. That's ridiculous for many reasons, not least because coal kills orders of magnitude more birds than wind per megawatt-hour, not to mention 20,000 Americans per year. The extent of opposition, and the irrationality of it, is surprising. You have to read original sources to get a sense of it. Take early aviation. Before 1908, practically no one believed that airplanes are real. The Scientific American printed vicious, irrational, unscientific attacks against claims, and the Wright brothers -- very similar to their attacks against cold fusion. (The Sci. Am. still has it in for the Wrights, repeating their nonsense attacks as recently as 2003.) In 1908 the Wrights demonstrated in France and in Washington DC and become famous overnight. They were on the front pages of newspapers worldwide. Hundreds of thousands of people saw them fly over the next several months. They were given awards by every country including a gold medal issued by Congress in 1909. Starting in 1909 there were air races with 10 or 20 pilots competing. So, you would think the controversy would end, wouldn't you? Nope. I have newspaper accounts and books describing events as late as 1912, where, for example, a person showed up with an airplane packed into railroad shipping containers in a Midwestern city, and advertised he would demonstrate flights before a paying crowd. He was arrested for fraud. The citizens threatened to tar and feather him because "everyone knows people can't fly." They sheriff told the pilot to get out of town in the dead of night. Apparently the citizens of that city thought the national press coverage was, in modern parlance, "fake news." They did not trust those big city newspapers. You see similar disbelief and opposition to things like self-driving cars today. There are many unfounded and hysterical claims about them. Someone in the comment section at the N. Y. Times said that a terrorist might use a self-driving car to drive on the sidewalk and mow down pedestrians, and it would not be the terrorist's fault because the robot is in charge. Obviously, the cars are programmed not to leave the road or run down anyone! Another letter claimed that thousands of self-driving cars on the New Jersey Turnpike might suddenly to exit to the island Service Centers. The letter writer seemed to think they might pile on top of one-another in a gigantic demolition derby, trying to occupy the same parking spaces. Again, obviously, a robot car that can drive in traffic would not try to park in a spot that was already taken. Such objections resemble one of the main objections made by scientists circa 1908 who did not believe airplanes were possible: "even if you can fly, there is no way to slow down and land safely." These people apparently never watched a pigeon turn up its wings to a steep angle of attack, spread its tail, stall, and land. That is exactly how an airplane lands, and you can be sure the Wright brothers knew that before they glided the first time. Here is a famous quote about how it is impossible to land an airplane: "And, granting complete success, imagine the proud possessor of the aeroplane darting through the air at a speed of several hundred feet per second! It is the speed alone that sustains him. Once he slackens his speed, down he begins to fall. He may, indeed, increase the inclination of his aeroplane. Then he increases the resistance necessary to move it. Once he stops he falls a dead mass. How shall he reach the ground without destroying his delicate machinery?" Source: Newcomb, Simon. *Outlook for the Flying Machine. The Independent*, October 22, 1903. http://www.foresight.org/news/negativeComments.html You can see that Prof. Newcomb is describing how to land an airplane, yet he does not even realize he is! If he were here, now, I would say: "Professor, you just answered your own question. All you need to do is glide to within a few feet above the ground and then do what you just described. You fall a dead mass the last few feet, and then roll to a stop." Most of the objections to cold fusion are similar. They are asked and answered. - Jed