Why do scientists keep pursuing fusion despite repeated setbacks?

[Tsunami]

Hey,

From a Philosophy of Science angle, I'm trying to argue why concepts (say, scientific hypotheses) survive even when they don't seem to be succesful. I thought a great example would be fusion.

Now, I'm not that big on particle physics (I've a Bachelor in Engineering Physics, but my main focus has been elsewhere), so I don't really have a clue what books/papers I should read into. What I'm looking for, basically, is:

-what reasons people have had to go looking for fusion technology; what theories supports this search
-why people believe in cold fusion; I know that hot fusion is basically what happens in the sun; but has cold fusion ever been demonstrated?
-my main thesis: I've the impression that as long as a certain concept leads to patterns of thinking that are unique and at least seemingly useful, then there's something about this concept that's scientifically valuable. I've no idea why this is, what this something is - I was hoping by investigation the science history of fusion this would become clearer.

So, can you put me on the right track? (This is entirely an indie project, not something I do for uni, just one of my many interests on the side... this is why an initial shove in the right direction is very welcome.)

 

[Astronuc]

Nice little intro -

In the late 1930s the German-born physicist Hans A. Bethe first recognized that the fusion of hydrogen nuclei to form deuterium is exoergic (i.e., there is a net release of energy) and, together with subsequent reactions, accounts for the energy source in stars.

http://www.britannica.com/eb/article-48320

Here is some background - http://hyperphysics.phy-astr.gsu.edu/Hbase/nucene/fusion.html#c1

http://hyperphysics.phy-astr.gsu.edu/Hbase/nucene/fuscon.html#c1


Cold fusion has not been demonstrated. It is nevertheless attractive since is overcomes the technological hurdles associated with high temperature plasmas and magnetic confinement, or the alternative inertial confinment, and the huge energy supply systems (i.e. high power lasers).