The purpose of this section of the dissertation is to assess the minimum level of certitude for the thesis proposed, with an additional comment of any suspected higher level of certitude. There are various levels of certitude that can be chosen. Opinion is defined as intellectual assent (or disagreement) given to one part of a contradiction with fear of the opposite.⁹³ Possibility is defined as the capacity for existence for a concrete possible thing: internally, that its constituent characteristics are not impossible, and additionally externally possible, if there is power to produce the thing.⁹⁴ Probability, also called likelihood, is defined as the weight of motives, or the accumulation of serious motives, for prudent assent to some proposition, which is intrinsic probability if the motive arises from the nature of the thing, and can be extrinsic probability if the motive is from authority, which can also suppose the internal motive.⁹⁵ Summary of Probabilities is defined as an accumulation of probable arguments, considered according to their force, which results from a mere juxtaposition. Convergence of Probabilities is defined as an accumulation of probabilities which converge to produce a sufficient reason. Moral certitude is defined as firm assent to one part of a contradiction whose necessity arises from the moral law in the physical (not ethical) sense, e.g., every mother instinctively loves. Physical certitude is defined as firm assent to one part of a contradiction whose necessity arises from the very physical nature of the thing, e.g., the law of gravity. Metaphysical certitude is defined as firm assent to one part of a contradiction whose necessity arises from metaphysical necessity, e.g., my own existence.⁹⁶

Certitude could arise from some observable fact or experiment. However, there is no experiment to prove evolution of the universe.⁹⁷ However, some restricted observation of evolution is possible by inspection of the earth and from the investigations of astronomy. Such evidence is growing due to modern instrumentation, such as radio telescopes, and by the possibility of placing telescopes in space. Further, as Donat notes from observation, there is no impossibility of "God cooperating with created causes," and "this we observe everywhere in other things."⁹⁸ Observation of inanimate objects in the universe, such as the heaven bodies, show them to contribute to the order and good of the whole universe.⁹⁹

Certitude could arise from some philosophical explanation that exists. Explanations were given by several Neo-Scholastics: Gredt,¹⁰⁰ Donat,¹⁰¹ Mondin,¹⁰² Hellin,¹⁰³ Hugon,¹⁰⁴ and Klubertanz.¹⁰⁵

Certitude could arise if the argumentation was based on some philosophical principles. Gredt seeks an explanation of cosmic evolution using the principle of causality (secondary causes) and the principle of sufficient reason.¹⁰⁶ Donat explores secondary causes¹⁰⁷ and the prime cause¹⁰⁸ of cosmic evolution, which together provide a sufficient reason. Sheilah O’Flynn Brennan argues cosmic evolution according to the principle of finality for dynamic order in the universe.¹⁰⁹

Certitude could arise if the explanation is sufficient, due to the principle of sufficient reason. Hellin considers astronomy, chemistry, biology and mineralogy to verify the sufficiency of his reasons.¹¹⁰

Certitude could arise if the explanation was rooted in St. Thomas Aquinas, thereby being faithful to tradition. St. Thomas portrays a dynamic universe in which "every creature is in service of the perfection of the universe", when St. Thomas teaches: "Every creature is in service of its own perfection. Second, creatures less noble are in service of the more noble, as lower creatures to man are (in service) for man. Further, every creature is in service of the perfection of the universe. Finally, the totality of the universe with all its parts is ordered to God as its goal" (Aquinas Summa Theologiae 1. 65. 2).¹¹¹

Certitude could arise if Neo-Scholastics agree on the possibility of evolution as the proximate cause of the universe, such as: Gredt, Donat, Klubertanz, Mondin, and Hellin.

Certitude could arise due to recent scientific confirmation by convergent scientific arguments. Gredt notes that astronomy shows diverse states of cosmic material and diverse celestial bodies, and this is proof of the continued evolution of the universe.¹¹² Soccorsi states in his conclusions about the current state of astronomy that terrestrial and celestial phenomena, solar nuclear fission, and the formation of stars and galaxies, "demand a special evolution of the universe, whose duration is also able to be estimated in its order of five billion years."¹¹³ Thus cosmic evolution is scientifically well based.

Certitude could arise if the opposite opinion is not tenable. Donat rejects the opposite opinion to an orderly evolution of the universe, which would be chance.¹¹⁴

Certitude could arise if the objections of adversaries are able to be answered, especially those of the atheists, who assert that cosmogonic evolution would render the Creator superfluous.¹¹⁵ However, Donat finds cosmic evolution very acceptable to God, and notes the cosmic evolution fits with divine perfection in the best way (optime) according to St. Thomas.¹¹⁶

Certitude can be had from the possibility of philosophers and theologians admitting this mode of origin without damage to their other beliefs. Nogar says, "Expressed in the language of the theologian, the laws of nature are the plan of God."¹¹⁷ Donat notes that the evolutionary cosmos agrees in an outstanding way with divine providence.¹¹⁸ Hugon says that current evolution of the world is "not unproven for philosophers," notes that there is nothing "inconvenient" in cosmic evolution, quotes Pesch to say cosmic evolution is "fitting"as a vestige of the creator. Admitting cosmic evolution after the universe was created by God does not fall under the censure of the First Vatican Council.¹¹⁹ The current Catholic media are open to cosmic evolution.¹²⁰

Certitude can be had from the fact that cosmic evolution is the best answer now for the present development of the universe.¹²¹ St. Thomas makes a distinction between a "verified" universal (dici de omni) and a "provisional" universal (ut nunc).¹²² This provisional universal, within a working hypothesis, is very useful in the investigation of nature. An example of a verified universal (dici de omni) is that in a right triangle every right angle has ninety degrees. An example of a provisional universal (ut nunc) is "white" predicated as a common property of swans, or evolution predicated as the common property of every origin of species. The example of the right triangle is a property based on certain (propter quid) demonstration. The example of the white swans is based on an incomplete (quo) induction, since the reporters had never seen a black swan. Thus, evolution predicated as cosmic evolution of already created matter is the best answer we have now.¹²³

The level of certitude for the "cosmic evolution is possible, but equivocal" is at the level of the metaphysically possible. The proof is the principle of finality.¹²⁴ In addition it can be argued that it fulfills the Principle of Expanding Goodness (Bonum est diffusivum sui), which is in the genus of final causality and also in the genus of efficient causality.¹²⁵ Further, the convergence of all of the above arguments are proof, especially the fulfillment of the principle of sufficient reason. This agrees with the opinion of Gredt who maintains that cosmic evolution now has the highest probability.¹²⁶ Donat says that the cosmic evolution can be seen by observation in the proximate formation of earth, and that this cosmic evolution is "certain."¹²⁷ Hugon says cosmic evolution is not unproven, is convenient, and quotes Pesch to say cosmic evolution is fitting; Hugon also notes that the scientific hypothesis is most probable (probabilissima).¹²⁸

Having come to the correct conclusion on the philosophical level of certitude, the philosopher must still conclude with some humility. The philosophy of nature does not disregard the objects observed and perceived by sense.¹²⁹ This is the method of Aristotle and St. Thomas.¹³⁰ St. Thomas notes that if "observation" can determine every single entity fits its own natural operation, all the more reason to maintain that creatures operate for the good of the universe.¹³¹ However, the science that underlies the theory of cosmic evolution is in the process of development.¹³² Beyond this, the mathematics of science also have a difficult time treating the problem of evolutionary cosmology.¹³³