You could look at a speed limit as a social contract. There are other positive reasons to go slower than avoiding death (gas mileage for one). However, if the

You could look at a speed limit as a social contract. There are other positive reasons to go slower than avoiding death (gas mileage for one). However, if there is an agreed upon legal limit, then by speeding you are violating that contract directly increasing the difference in speed therefore increasing the chance of an accident.