[smallnamespace]

> So why do we talk so imprecisely about objects as if they have permanence? Why is it the same river the next time we step in it?

Why do most languages allow variables to mutate, rather than forcing us to write in static single assignment style?

Because it is useful; the imprecise name still communicates something of value to both parties: that variable foo and variable foo', although not identical, are joined by a common purpose.