It is not a presupposition, it is a conclusion.
Every conclusion began with certain presuppositions. [Linked Image] Moreover, to deny that presuppositions exist in the Old Earth Theory (OET) is not only a presupposition itself, but a very definite giggle joke.

Look at the history of the formation (of the scientific principle) of geological ages, it was dominated by Christians who did NOT want to see long ages but wanted to find geological evidence for a young earth.
Do you remember reading about, Buffon who was a deist or secret atheist, as were Lamarck and Hutton. Laplace was an open atheist. Werner, Cuvier, Smith, and Lyell were probably deists or some sort of vague theists. These developers of OET were hardly objective, unbiased, let-the-facts-speak-for-themselves observers of the physical evidence. As Terry Mortenson, Ph.D. concludes, “the Genesis-geology debate was really a conflict of worldviews—that is, deism, vague forms of theism and atheism joined together against biblical Christianity….While these old-earth proponents had varied opinions about the existence of God, they all rejected the God who is revealed in Scripture and operated with the assumptions of philosophical naturalism in their interpretation of the astronomical and geological evidence.”

As Nevins wrote so many years ago,

Historical geology is the field of study which seeks to decipher the clues and records bearing on the earth's history. Since the historical geologist cannot observe the history he attempts to interpret (he cannot relive ancient times), scientific methods involving repeatable observation and experimentation cannot be utilized. The method relied upon is much like that used by a detective as he seeks to unravel the many evidences and furnish a tentative description of a crime. The conclusions reached by the historical geologist, as those of the detective, rely on numerous assumptions and much fragmentary evidence making scientific proof impossible. The conclusions made in any type of historical investigation—no matter how "scientific" they are claimed to be—depend largely on the basic conceptual framework (values, beliefs, and methodology) used by the investigator.
Unlike geology and a host of other so-called scientific evidence, the inerrant Word of God is not based upon numerous assumptions, but on God himself. However, the interpretation of Word of God can be faulty if our study is not based upon a proper hermetical framework for interpretation. A proper hermeneutical framework does not include “improvable" science, but Sola Scriptura. Are you going to believe The Rock or an unsupported tale about a rock? scratchchin

Please read the article BIBLICAL PRESUPPOSITIONS AND HISTORICAL GEOLOGY: A CASE STUDY (the normal disclaimers apply).

Reformed and Always Reforming,