starship-design: Paradox

["L. Parker" <lparker@cacaphony.net>]

Timothy,

I tend to take the position that time travel is either:

a) impossible, or
b) possible but causality conserved (I invented that phrase).

I withhold judgement on a) for lack of observational evidence ;-)

For b) basically what I mean is that if there were paradoxes we 
should be able to design a thought experiment to prove or disprove 
them. Since we haven't, and lots of people have tried, I think that 
no matter what you can't have a paradox or at least not one which 
is observable which amounts to the same thing.

Like the theory of gravity, I can offer no mechanism by which this is 
so, this just seems to make sense in light of what we currently know.

Does anyone know of any arguments that would tend to prove or disprove 
the case for paradoxes? I don't mean FTL in particular, just time travel 
paradoxes.

Lee