Granted, our concepts are often unclear.The Socratic dialogs demonstrate that, when pressed, we have trouble explaining our concepts. But that doesn't mean that we don't know what things are well enough to use the concepts. People managed to communicate and survive and thrive, probably often using some of the very concepts that Socrates was able to shatter with probing questions. For example, a child's concepts of "up" and "down" unravel slightly when the child learns that the planet is a sphere, but that doesn't mean that, for everyday use, the concepts aren't just fine.