The approximation of all modern measurements, due to our state of fallen human nature, is one thing and does not take away the certitude supplied by the metaphysical principles of existence-essence, act-potency, form-matter and substance with its nine accidental properties. Probability, then, is just the uncertainty of the inductive method which must always leave open the possibility, or even probability of some thing or event that would alter, in some necessary or significant way, a physical model and its predictions. Such, for example, is the geophysical theory and model of uniformitarianism, that processes have always and will continue to operate as they do in the present. This theory was summed up by Scottish scientist James Hutton in the 1790's, when he dogmatically concluded that since he could find no vestige of a beginning, nor any prospect of an end, therefore..... But he should have read all of the great Roman poet Lucretius, because the epic, De Natura Rerum, very emphatically and clearly, while asserting the cyclic nature of the Order of Generation and Corruption, at the same time recognized the "fixity of species", and made it impossible for anyone to claim a transformation of species and remain in the domain of sanity.
But Charles Lyell, in the early 19th century, seemed to give scientific credibility to Hutton's theory by his Principles of Geology, based on newly discovered strata in the earth's crust with their innumerable fossils. "Read all about it" in the copious literature. See how Darwin was instructed by his predecessors and his peers to see a "record" of past ages in the strata-containing fossils. It is a long and fascinating story, nor is it free from political connections. The Whig party in England, with its goal as the permanent destruction of the monarchy, in league with similar anarchic-liberal factions in Europe, and the control exercised in all the universities and societies, such as the Royal Society of England - all these political and economic movements were intensely interested in what was going on in the sciences, as they still are! And here is the intrinsic connection between so-called theoretical science and Baconian utilitarian, experimental, empirical or technological sciences. These latter are constantly running up against that "fixity of species" that Lucretius recognized and that the latest experiments with the hapless fruit fly continue to prove.