[cjfd]

Actually, it does. Because of relativity events that occur at the same time in one frame of reference do not occur at the same time in another. A delay of zero between two different points implies that there is a reference frame where the delay is negative.

[soulofmischief]

Relativity was derived as a direct consequence of imposing an invariant speed of causality to the Lorentz transformations, therefore it cannot tautologically be used as justification for an invariant speed of causality.

[cjfd]

"Imposing an invariant speed of causality to the Lorentz transformations" does not sound quite right. I think it is more like assuming that the Lorentz transformations are the true symmetry of mechanics. If one wants to keep that causal, there cannot be information moving faster than the speed of light because there is a reference frame where said information would be moving backwards in time.

[Etheryte]

I'm not sure that holds when you take the speed of light to be infinite. Depending on which end you look at it, you'll either be dividing by zero or having infinite energy, so I don't think relativity the way we understand it would still make sense in any way.

[cjfd]

Well, it is quite well known what you get when taking the speed of light to infinity. It is classical mechanics.

[Etheryte]

Point being, in that case you don't have relativistic effects nor effects preceding causes and whatnot.