What kind of evidence is given in the excerpt from Lincoln's First Inaugural Address?

Explanation: Descending from these general principles, we find the proposition that in legal contemplation the Union is perpetual confirmed by the history of the Union itself. The Union is much older than the Constitution. It was formed, in fact, by the Articles of Association in 1774. It was matured and continued by the Declaration of Independence in 1776. It was further matured, and the faith of all the then thirteen States expressly plighted and engaged that it should be perpetual, by the Articles of Confederation in 1778. And, finally, in 1787 one of the declared objects for ordaining and establishing the Constitution was "TO FORM A MORE PERFECT UNION."