Except you forgot the part where old ideas are revisited as new information becomes available and old theories and postulates are re-evaluated. In your world of science, Newton would be king and Einstien would not have bothered to think about any of what he did. What's more, a lot of people would be a lot happier, smug in their knowledge that classical physics was immutable.
At no point do I say that credence should be given to the claims of the perpetual motion dreamers...just that consideration should be given to their ideas before rejecting them on the basis of known physical laws and, keeping open the possibility that new informatilon may require new thoughts (ie: perhaps "known physical laws" are not quite so well known as we may think).
So, I guess, I'm saying that I patently disagree with your conclusion that keeping an open mind (or even allowing some doubt) is unacceptable behavior for a person of science.
Actually, I agree that an open mind is vital to science. However, that does not mean that an idea should be entertained when there is already a mountain of experimental evidence to show that the idea will not work.
In Einstein's case, there was no experimental evidence to say his ideas would not work--that's why he did the work in the first place, to try to explain existing results which could not be explained by the theories of the time. His ideas were found to be testable. They were tested. The test results confirmed what his ideas predicted. After enough repetitions of the tests, the ideas were accepted as valid theories.
What you are forgetting is that the scientific method starts from an observation, not a hope. You observe something, make a prediction (hypothesis) about it, then devise an experiment to test that prediction. If the experiment is negative, you make another prediction and test that. If the experiment is positive, you repeat the test to make sure it wasn't a fluke. If it's still positive, you try to get other people to examine the test methodology, reproduce the test, and confirm the results without your involvement. If the results are still positive, and an experiment cannot be devised which shows the hypothesis to be false, then you can accept the hypothesis--at least until it is disproven.
What crackpots do is break this chain, have no independently verifiable results, and then bellyache that the "establishment" is against them. Part of the problem is that to get the results they attempt to get to in the first stage, several other stages are skipped along the way. Instead of formulating hypotheses and testing them independently and thoroughly to ensure that the ideas are sound, they consistently wibble on about what they hope to achieve but offer no sound experimental evidence on which to base their claims.
If
any part of the idea presented contravenes current understandings and theories, that part must be subjected to thorough testing to ensure that it performs as predicted by the presenter. If the results appear to break any existing rules, then all possible reasons for this must be eliminated until only the impossible remains. (By "impossible" I mean that it is performing in a way which cannot be currently explained.) On the off chance that the device is performing in an unexplainable way then the search would be on for an explanation. That doesn't happen a lot for crackpots.
The typical crackpot methodology is to simply decide that some idea really seems like it should work, then announce that they're building WonderDevice 2009. They offer no testable hypotheses nor experimental results to explain why the device might work, but instead dive right in to start building it. Even worse are the people who actually sell these ideas, and perhaps even the people who buy them and then think that the reason they can't get help about them is that the old boys' club or establishment is against them, when the reason is really that nobody wants to waste their time on ideas which have an obviously fatal flaw which hasn't been experimentally addressed.
Of course our current theories do not explain everything. However, these crackpot ideas do not address the things which are not understood. They just try to get something for nothing because "jeez dude, that really seemed like it would work".
Torben