asdf ) gurgled happily, sounding much like they
were saying :

The "safety" argument only bears up to logical scrutiny if you follow
through to "All speeds below the limit are therefore safe" which is
patently absurd.

It suggests that "all speeds above the limit are unsafe".

Which is obviously completely absurd.

This is not the same as "all speeds below the limit are safe".

The logic certainly follows.

rehashes from uk.rec.driving earlier this week

If speed limits need to be set and rigorously enforced for safety, then
that presupposes that no driver is competent to identify and set a speed
which may be above the prevailing speed limit, yet which is safe for the
circumstances they face. If that is the case, then, since there is no
difference in the driver's cognitive processes and their ability to define
a set speed between travelling at a speed above and one below the speed
limit, then drivers must be presupposed to be incapable of identifying and
setting a speed which is safe for the conditions whilst below the speed
limit. Because of that, speed limits must therefore be set at a point at
which all drivers in all vehicles are safe at all times below the speed
limit. Which is quite obviously absurd.

Therefore, speed limits can not be set and rigidly enforced primarily for
safety.

For that to be implied, you'd have to automatically become immune to
prosecution for dangerous/careless driving (etc) if you were below the
speed limit.

Yes, that's *exactly* what saying "Speed Kills" and placing all the focus
on rigid enforcement of limits does. Stupid, isn't it?