The following discussion between Ron Paul and Larry King touched on one of the most intellectually bankrupt arguments employed by many who are unwilling to do serious thought. King recalled, "Lyndon Johnson once said, 'The probable answer is that a government is going to have to be half-capitalistic and half-socialistic.'" This argument can be stated in many different ways, as promoting balance, as an objection to extremism, etc. Of course, these are all just platitudes with no real thought behind them.
Such ideas as balance and moderation sound good. Humans seek to avoid conflict and controversy (most of us, anyway) and so many are willing to accept a balance, or compromise, as being desirable. Furthermore, we accept the concept of moderation in nature and biology. e.g. It's good to let your kids get dirty and build up their immune systems, but it's also good to teach them good hygiene. It's good to get some vitamin A, but not too much. etc. ad infinitum.
Around the same time Johnson was making such empty remarks, Barry Goldwater famously said, "Moderation in the pursuit of justice is no virtue, and extremism in defense of liberty is no vice." Now there is a well-reasoned statement.
Theoretical concepts like liberty and market intervention do not work the way that many other things work in biology and other sciences. There is a real provable reason why a balance of vitamin A is optimal vs. avoiding it altogether or taking it in abundance. A dietitian didn't just come up with the answer that moderation is best, nor did he just make up what constitutes moderation. Actual thinking and experimental science went into showing why it is so.
On the other hand, pursuing a balance between government and liberty confronts both philosophical and scientific problems. Those pursuing moderation have either failed to address either of these problems, or they have failed in their study of history and philosophy to understand their error.
(Ron Paul on Larry King Live [29/10/2009] following Michael Moore)