I am not sure how you define “science” here. Do you mean “natural science”? It, too, is
a division of the speculative sciences which in turn are a part of philosophy.
Also, how do you define "ontological causality?
“Then of what is he speaking?”
He should" according to whom?
In regard to methodological naturalism the history of science has shown that this approach is most productive and most objective. If individual religious beliefs, philosophical positions, and ideologies are left out of scientific investigations or ignored (to ignore is very different than to deny), then science because more objective. Clearly, the experiments and conclusions of one scientist can be verified by another regardless of their differing non-scientific beliefs. In fact, the natural sciences truly advanced when scientists began leaving final causes out of their explanations of natural phenomena. Final causes are now left to the philosopher. I am not aware of any prominent scientist today who disagrees with methodological naturalism as most appropriate.
Regarding St. Paul’s statement, he is referring to
gnontes, which is an inceptive, speculative sort of knowledge about God. I might even characterize that kind knowledge as quasi-philosophical, but with some individuals it is more intuitive. This knowledge of God’s existence comes from reflection on nature, its order, design, beauty, or goodness. It is not something quantifiable or verified by scientific methodology.
Gnontes is not derived from philosophical demonstration such the Aristotelian demonstration for the existence of a First Cause. I’m sure St. Paul realized very few Gentiles were knowledgeable in Aristotelian philosophy or even the sciences of the day. So, he is speaking about a knowledge of God’s existence that is available to all, however imperfect that knowledge may be. That is why he says the Gentiles are without excuse. They would have plenty excuses if the knowledge of God he talked about was a scientific or strictly philosophical knowledge.
Philosophy and natural science: I cannot explain this well in less than a few pages but I will point out some highlights. Philosophy differs from the natural sciences in its formal object. This is a distinction worked out in the Church over a long period, and that insight allowed the particular sciences to develop on their own.
The categorization now differs a bit from that of Boethius. One of the distinctions is the recognition of a physics that is a part of philosophy and a physics that stands at the head of the natural sciences. Mathematics was categorized by Aristotle and Aquinas as under philosophy because of its degree of abstraction. Currently, mathematics can be considered midway between the natural sciences and philosophy, though there are variations in categorizing mathematics.
Both philosophy and the sciences have disciplines that are speculative or theoretical and practical. So the division between philo and science is not based upon speculative versus practical.
Within the subject matter common to the sciences and philosophy, we say that the aim of science is know what is universally observable about the nature of physical things, while the aim of philosophy is to know what is universally intelligible about their natures, that is, their substance (ousia) and their causes.
The formal object of philosophy is the
noumenal or
intelligible order, that is, things in the principles and causes of their being.
The formal object of the natural sciences is the
phenomenal order, that is, sensible things in their operations and changes. The natural sciences are limited to studying the changing surface of things in nature. This study includes classification, systematization, correlation, quantification and so on.
I know there is much more to be said for a full explanation, but I have to get back to work now, and will finish up by making a brief comment about J.S. Bell. The conclusive character of quantum mechanics, in its dis-allowance of absolutely precise measurements of quantum interactions derived further experimental support from Bell’s theorem of inequality. However shored up this may be it does nothing to address the issue of whether a restriction on precise measurement entails an ontological incompleteness in the interactions measured.
That reminds me that you asked about ontology. In the interest of time I will provide a link to the Catholic Encyclopedia article on
Ontology.