Many Americans today go far beyond simply rejecting the ideas of the American founders, the claims of the Declaration, and the Constitution.  They reject the very idea of truth.  These Americans were taught in American universities that there is no such thing as truth, that truth is an outmoded concept, that we now live in a post-truth reality.  The belief that the concept of truth is outmoded is no longer confined to academia.  It has invaded the world outside academia and won a great victory there; the Oxford Dictionaries selected "post-truth" as the Word of the Year for 2016.

And a great victory it is.  Convincing Americans that there is no such thing as truth defeats the very foundation of the American idea.  The Founders, famously, founded America on certain truths, truths they declared to the world were not only true, but self-evidently true: "We hold these truths to be self-evident…"  Self-evident truth occupies the first place and also the highest position among the declarations of the Declaration of Independence.  "Created equal" and "unalienable rights" and all the rest follow along after that bold opening claim.

The Founders certainly believed they built on the rock of self-evident truth.  But if there is no such thing as truth, then there can be no such thing as a self-evident truth, and everything the Founders declared and established can simply be dismissed.  There is no need to try to understand the thinking of the Founders — not even by professors of constitutional law.

A few years ago, I watched a broadcast of an academic conference on the Constitution.  The participants were all professors of constitutional law from major American universities.  The keynote speaker declared for himself and for his colleagues their indifference to the ideas of the Founders.  He developed his theme at some length to repeated enthusiastic applause from his fellow professors in the audience.

However, if you as an American citizen decide to take an interest in the ideas of the Founders, you quickly run into their idea of self-evident truth; it is everywhere in their writings.  Sometimes you may not realize it, though.  For example, consider a passage written by Alexander Hamilton.  Please read Hamilton's words carefully before you move on to reading what I have to say about them.  The passage is from Federalist 31:

In disquisitions [discourses] of every kind, there are certain primary truths, or first principles, upon which all subsequent reasonings must depend. These contain an internal evidence which, antecedent to all reflection or combination, commands the assent of the mind.

The passage may be easier to understand with the explanation that "primary truths" and "first principles" are alternative ways in which the Founders referred to self-evident truths.  Consequently, we can restate Hamilton's words in a way that gives them a more familiar feeling: "there are certain self-evident truths upon which all subsequent reasonings must depend."  Restated in this way, it becomes clear that Hamilton's statement parallels Jefferson's iconic one in the Declaration.  Hamilton and Jefferson are relying on a shared understanding of self-evident truth — and Hamilton's passage, like the Declaration, gives self-evident truth the highest position.

What is that shared understanding of self-evident truth that Jefferson and Hamilton and the other Founders relied on?  It is this: to know that a statement is self-evidently true, all that is required is that we understand the statement; to understand a self-evident truth is to know that it is true.

Does this idea of statements that are self-evidently true seem a bit high-flown, something for special occasions such as a speech celebrating the Fourth of July?  Actually, it shouldn't seem unusual because we make use of the same understanding of self-evident truth all the time.  The idea of self-evident truth has been carefully excised from our political discourse, yet we constantly rely on the self-evidence of truth in our day-to-day lives, though we may not always notice it when we do.  Here is an example of the kind of thing we do all the time, selected from a book on economics entitled Cents and Sensibility:

Without Columbus someone else would have discovered America, but it defies common sense to assert that without Milton someone else would have written Paradise Lost.

Both the claim about Columbus and the claim about Milton are self-evidently true; to understand them is to know they are true.  We could re-state them in this way: "it is a self-evident truth that without Columbus someone would have discovered America, and it is a self-evident truth that without Milton Paradise Lost would never have been written."  Such statements, as Hamilton puts it, "command the assent of the mind."

A self-evident truth does not need a proof; it only needs to be understood.  If a university assembled a committee of scholars and spent years and millions of dollars examining those statements about Columbus and Milton, absolutely nothing would be gained.  When the scholars issued their report, people would be right to say it was a waste of time and money.  However, most of us would probably not make reference to self-evident truths to make that point.  Instead of saying there was no need for the all the expenditure of time and money because the statements are self-evidently true, we would be more likely to say it was a waste of time and money because "it's just common sense." 

The Founders would agree with us, though they might want to help our understanding along by pointing out the difference between a self-evident truth and our capacity to recognize a self-evident truth.

Common sense gives us the capacity to recognize what is self-evidently true, and using common sense to recognize what is self-evidently true is something we do all the time.  And every time we do, we disprove the claims of those who defy common sense by claiming that there is no such thing as truth.

Robert Curry serves on the Board of Directors of the Claremont Institute.  He is the author of Reclaiming Common Sense: Finding Truth in a Post-Truth World and Common Sense Nation: Unlocking the Forgotten Power of the American Idea.  Both are published by Encounter Books.