> you cannot ask a customer of a building to specify what strength concrete needs to be used. Indirectly, you can. They'll specify how many floors there needs

> you cannot ask a customer of a building to specify what strength concrete needs to be used. Indirectly, you can. They'll specify how many floors there needs to be, and combined with automatically-specified things like gravity and local weather phenomena, you can derive what building materials you can safely use.