| Which philosophical theory? Constitutionally Montesquieu and Locke had a profound influence. (Ever hear of Life, Liberty, and the Pursuit of Happiness? Locke wrote Life, Liberty and Estate.) American philosophers around the time of the "Founding Fathers" were theorists in their own right.
To describe it today is far more complicated. The nation is so diverse with a colourful history. The differences in the Declaration of Independence and the Constitution just begins to illustrate the US' diversity. Manifest Destiny, the Great Awakening, the religious foundations of early settlers, the philosophy around slavery all had their time and continue to influence the American mindset.
And you'll never understand the west just by looking at the US; for starters, the US and Europe have diverged on many paths. |