Wittgenstein on accurate, precise and useful

From Philosophical Investigations by Ludwig Wittgenstein

To repeat, we can draw a boundary - for a special purpose. Does it take that to make the concept usable? Not at all! (Except for that special purpose.) No more than it took the definition: 1 pace = 75 cm. to make the measure of length ‘one pace’ usable. And if you want to say “But still, before that it wasn’t an exact measure”, then I reply: very well, it was an exact one. – Though you still owe me a definition of exactness. . . . Is it even always an advantage to replace an indistinct picture by a sharp one? Isn’t the indistinct one often exactly what we need?

In many discussions we sling around terms that have some implication of a boundary but, when you investigate, has not so much a boundary as a loose, undefined and unguarded frontier, subject to change, and including some things people don't expect and excluding others they were certain were within the boundary.

Precision, accuracy and usefulness are important concepts that are often at the crux of many disagreements.