I don&#x27;t disbelieve in cold fusion, the EM drive, superluminal anything, solve-all-problems nanotech, or the singularity because of the reputation of scientists.<p>I disbelieve them because pessimism.  They&#x27;re just such... &quot;wouldn&#x27;t it be great if&quot; results.  Wouldn&#x27;t it be great if we had cheap, limitless, clean energy?  Wouldn&#x27;t it be great if we were not subject to the tyranny of the rocket equation?  Wouldn&#x27;t it be great if the stars really were in reach?  Wouldn&#x27;t it be great if all material needs were going to be met in the next generation?  Wouldn&#x27;t it be great if we were going to achieve godhead?<p>It would be great.  It&#x27;s so great that I just don&#x27;t see it happening.  It sounds like a myth people tell themselves.<p>This is admittedly not a logically coherent dismissal.  But you can&#x27;t derive anything from base principles, and if you have to have a heuristic, I think it&#x27;s a more useful heuristic than a reputation-based one.