I present you the ultimate proof that Jack actually caused the incident.
First thing's first:Let's Review The grandfather Paradox for those who don't know it.
"Say you invent a time muchine you go back in time and accidently kill your grandfather before he meets your grandmother then you would have not been conceived therefore you don't invent the time muchine and you don't kill your grandpa so you are conceived which Allows you to invent a time muchine and kill your grandfather again so you will be stuck in an endless time loop"
This is the same deal"The incident happens in 1977 which leads to the construction of the swan and Desmond killing Kelvin and be late for the button so Flight 815 crashes. They spend 108 days they leave,they return in 1977. so if they have been successful in preventing the incident then there will be no Swan No Desmond Killing Kelvin no Desmond Crashing Flight 815 so They don't spend 108 days they don't leave they don't return in 1977 so they will be unable to prevent the incident...Bla..Bla...Bla"
The point is:If they prevent the incident they will be stuck in an endless time loop which will repeat forever and It's just not Lost Material.
What do you think?