Philosophers have their "parties," just like Democrats and Republicans. If the Rationalists were one, the Empiricists were the other. "Empiricism" is the belief that ideas are derived from experience through the senses, not from reason in and of itself. Let's watch them come to a bloody end, just like the Rationalists.

Their story begins with John Locke (1632-1702). A student of philosophy, natural science, and medicine at Oxford, he was an important politician in England. His primary philosophical concern was with epistemology (the theory of knowledge). And his ideas have shaped the way Americans see ideas ever since.

Locke reasoned that we are born with our minds a "tabula rasa" ("blank slate"). All we know comes from experience, writing on these "slates." Our sensations (coming directly from experience) and reflections (upon sensations) produce knowledge. We must be satisfied with probability, since our senses can deceive us (agreeing with the ancient Skeptics).

Locke applied this epistemology to politics in defense of democracy. We learn moral law only from experience, and desire to pursue pleasure and avoid pain. This desire should be protected by the government, so that our "inalienable right" to the pursuit of happiness is preserved. No Locke, no Thomas Jefferson.

Keep going: empiricism in theology leads to Deism. The only fact you can state about God is that he is the creator of the world (we had to come from somewhere or Someone). Everything else is the result of individual, subjective experiences. So we posit a God who made the world but does not participate in it today, and we have Deism (with Locke its father). Again, no Locke, no Jefferson.

From Locke we move to George Berkeley (1685-1753). This Irishman, Bishop of Cloyne and missionary to Rhode Island wrote his Treatise Concerning the Principles of Human Knowledge in 1710. He took Locke a step further: if all we know comes from experience, then the world as we know it can only be the world we perceive. This is "solipsism": "to be is to be perceived." Berkeley reasoned that God perceives all that is, which is why the world holds together when we're not looking. But he couldn't prove that it was so by objective experience.

So David Hume (1711-1776) took the stage, and empiricism to its logical conclusions. His Treatise on Human Nature (published when he was 26 years of age) and Inquiry Concerning Human Understanding argued this basic thesis: where there is no impression there can be no knowledge. Hume denied even causality as non-empirical.

He thus denied the cosmological (from Creator to cosmos) and teleological (from Designer to design) arguments for God. His radical empiricism led ultimately to the death of empiricism. For ultimately, if Hume is right, we can know nothing. As a result, Hume is called the "Father of Skepticism." From Descartes' "doubting is thinking," we have come to Hume's "doubting is doubting." Another dead end.