Paul Rosenberg in Al Jazeera:
This philosophy prized individual critical inquiry, as well as institutions-formal and informal-which enabled individual efforts to be joined together into a far more powerful whole. This outlook was crucially important to the creation of a new nation on a new hemisphere, confident enough to establish itself on a new political foundation with some ancient roots, but fashioned with its own original design. Mere imitation of the past was rejected as a guiding principal. So, too, was blind reliance on the fantasy of individual political genius. Instead, the spirit and process of critical inquiry was crucial to how the new nation was conceived.
The basic architecture of “separation of powers”, for example, was intended to prevent the accumulation of all power into the hands of any unaccountable group or faction – and thus to put a premium on the process of advancing ideas that could pass the muster of critical examination by the widest possible range of parties involved. Similarly, steps were taken to insulating of government from dogmatic religious influence. Religious tests for public office were banned in the Constitution itself, and separation of church and state was formalised in the First Amendment's guarantee of religious freedom, which similarly guaranteed freedom of speech, freedom of assembly and freedom of the press – all intimately connected to the individual and collective exercise of critical reason.
And yet, despite all this, there was always an anti-Enlightenment, anti-intellectual side of America as well. And that side has always created needless deficits in critical thinking, hampering America's ability to fully realize its promise.
More here.