Can The Nature Of Nature Be Determined With Nature?

In what way is the assertion, “nature is self-existing” derived from “observation, experimentation, and rational analysis?” Secular Humanism claims that it derives its knowledge from this process, but knowledge of self-existing matter is unavailable by current scientific procedures. The claim that nature is self-existing is objectively untestable because we have no framework for defining and identify self-existing matter. There is no experiment that can show the difference between contingent matter⁠1 and self-existing matter.
To identify self-existing matter One would need both types of matter, contingent and self-existent, to observe, experiment, and analyze. To determine if the current form of nature is truly self-existing or contingent, there would have to be a control group made up of self-existing matter, and a test group to observe, compare, and analyze. This is obviously an absurd scenario. 
Therefore the knowledge of “self-existing nature” does not abide by the basic tenants of Humanism, that knowledge should be derived by science. The scientific process is natural, and confined to nature. To develop a description of nature as a whole from a process confined to nature is absurd. It would be like saying, “we will use nature to measure nature, so that we can find out the nature of nature.” 
Since knowledge comes from science, and science can’t find the nature of nature, the assertion that the universe is self-existent should be rejected by Secular Humanism. However, it has appeared in the Humanist Manifestos from the first in 1933 and the latest in 2003. Rather than restrict itself to knowledge that was derived in that way, the Humanist Manifestos make untestable, unverified, and dubious claims. This is a denial of the logical conclusions. 
The short but profound statement, “nature is self-existing,” is not only contradictory to the previous espoused epistemology of the Secular Humanist Manifesto, but it adds no strength to this worldview. In fact, this unsupportable statement goes a long way in demonstrating this ideologies weakness. 
All that atheistic humanism has done here is subtract a causally dependent explanation of origin. It stops short of replacing what it subtracted with something viable or substantive. Instead, the secular humanist worldview simply injects an unsupportable assertion, for no apparent reason at all.  This subtraction does nothing to improve upon the alternative viewpoint, which is cosmological contingency.⁠2 A self-existing universe gives no philosophical advantage in method or approach. As William Lane Craig wrote, “I see no good reason for methodological naturalism in either science or history.”⁠3 There is no practical or productive reason to hold to self-existing nature. It gives no pragmatic advantage.

1 Contingent matter is that which casually dependent. It is matter that exists by way of a creative process. It is contingent because it can not exist autonomous from the process which created it.
2 Cosmological contingency is the idea that the universe began as the effect of a cause, and therefore did not exist eternally.

3 Craig, William Lane. Reasonable Faith: Christian truth and apologetics. Crossway, (2008): 240.