In the Western world there are conservative liberals, liberal liberals, and radical liberals, says David T. Koyzis, but all adhere to the basic principles of liberalism:
The liberalism of Thomas Hobbes and John Locke. Of Thomas Jefferson and John Stuart Mill. After all, the Declaration of Independence is a liberal document, unquestioningly accepting that popular consent stands at the origin of political authority. As Alasdair MacIntyre has put it, in the Western world there are conservative liberals, liberal liberals, and radical liberals, but all adhere to the basic principles of liberalism.
So what accounts for the differences between Democrats and Republicans, between Barack Obama and Mitt Romney? What separates them is that each represents a different stage in the larger development of liberalism. Those who do not like what liberalism has become in recent decades have not repudiated it as such but have tried instead to hold onto it and return it to an earlier form—one thought to be purer and closer to its original meaning. I believe liberalism can be traced through five stages of development.