Liberal thinkers, with very few exceptions, fall cleanly into six categories. Four are historical, two are current. But even the best of these is far from pure. The strongest thinker, Aristotle (384-322 BC), never once said there was no such thing as god. And he discussed the "soul" endlessly. The next strongest thinker, Ayn Rand (1905-1982 AD), disbelieved in relativity, evolution, and the Big Bang. And she created a cult more than a philosophic school.

But atheism and science are integral to liberalism. The unreasonableness and rank illiberalism of mythology and pseudo-science are anathema to a healthy lifestyle and civilized society. The attitudes, beliefs, and practices of Aristotle and Rand were sometimes highly irrational. So even the finest of proto-liberal thinkers are far from being true or pure liberals.

Still, we have to work with what we've got, so here is the best so far: