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.⁵⁸ 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.⁵⁹ 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.⁶⁰ 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.⁶¹

Certitude could arise from some observable fact or experiment. However, there is no experiment to prove evolution.⁶² There is some restricted observation of evolution possible within species.⁶³ Observation, however, shows evolution cannot be explained by Materialism, since observation of the material alone does not distinguish between inanimate matter and animate matter.⁶⁴ "The theory (of Monistic Materialism) is inadequate, because it fails to give an explanation of ‘the whole man’," says Bittle.⁶⁵ Further, if nothing exists but matter and material energy, everything in man must be able to be interpreted strictly in terms of matter and material energy. Unexplained is the ordinary phenomena of sensation; the sensation of "blue" is totally different from the physical stimulus of a definite frequency of light waves striking the retina. Unexplained is cognition and consciousness by the material movements of the substance of the brain. Unexplained are abstract and universal ideas, while everything material is concrete and particular. Unexplained is intellection which is spiritual and intrinsically independent of material conditions, so that it cannot be reduced to material activity. Unexplained is the human mind, even if Materialism can explain the human body.

Certitude could arise from some philosophical explanation that exists for Materialism as an explanation of evolution or life in general. However, refutations of Materialism were given by several Neo-Scholastics: Palmes,⁶⁶ Bittle,⁶⁷ Hugon.⁶⁸

Certitude could arise if the argumentation was based on some philosophical principle, but the principle of causality rejects Materialism as the vital principle. This argument from the principle of causality states that the effect cannot be greater than the cause. But, Materialism (cause) cannot yield life (greater effect). Therefore, Materialism cannot be the cause of life and its continued evolution.

Certitude could arise if the explanation is sufficient, but the Materialists themselves argue against the facts, according to La Vecchia.⁶⁹ Metaphysically, it is clear that prime matter needs substantial form to create a composite, so an explanation by Materialism alone is not sufficient.⁷⁰

Certitude could arise if the explanation was rooted in St. Thomas Aquinas, thereby being faithful to tradition. However, Aquinas would affirm that Evolutionism is incompatible with Materialism, because it would be an error to judge forms (ens quo) as if substances (ens quod).⁷¹ Also, Materialism is inadequate to explain the vital principle. St. Thomas affirms the error of those who make the soul the same as the material body. St. Thomas teaches: "Others are more in error, who make the soul to be the body. Their opinions, although diverse and varied, are all refuted together as follows. Living beings, since they are natural things, are composites from material and form. They are composed of body and soul, which makes living things actual. Therefore, it is necessary that one of these be form and the other matter. The body is not able to be form, because the body is not ‘in’ another, as in matter or in the subject. Thus, the soul is the form. Therefore, (the soul) is not the body, because no body is form" (Aquinas Summa Theologiae 1. 75. 1).⁷²

Certitude could arise if Neo-Scholastics agree, but their agreement rejects Materialism. Examples of this rejection are: Calcagno,⁷³ Donat,⁷⁴ Givaert,⁷⁵ Palmes.⁷⁶

Certitude could arise due to recent scientific confirmation by convergent scientific arguments, but Materialism cannot account for scientific laws, the constancy of ever-recurring effects.⁷⁷

Certitude could arise if the opposite opinion is not tenable, but it is Materialism that appears untenable.⁷⁸ Also Materialism is not the only alternative in opposition to Dualism and Idealism⁷⁹

Certitude could arise if the objections of adversaries are able to be answered.⁸⁰ However, the Materialists are the adversaries in this case, and all their objections can be answered.

OBJECTION: Life consists in a marvelous harmony of diverse elements. But harmony is not something substantial, rather consisting in the disposition of accidents. Therefore, life does not demand substance. REPLY: Harmony is the exercise of life, something accidental, we concede. However, the question here is not about the exercise of life, but what causes that exercise.

OBJECTION: A substance is either a body or a spirit. But the vital principle in plants and animals is not spirit. Therefore, the vital principle is corporeal. REPLY: Distinguish the major that a complete substance (quod) is either body or spirit; the vital principle can be an incomplete substance (quo) and intrinsically dependent on material, so is neither body nor spirit.

OBJECTION: The vital principle moves a body by contact. But contact is not able to be done except between bodies. Thus, the vital principle is a body. REPLY: Distinguish the major: the vital principle moves a body by contact of power, intrinsically, formally and substantially constituting it, and so elevating its corporal powers to operation virtually, concede; moves a body mechanically, deny.

Certitude can be had from the possibility of philosophers and theologians admitting Materialism without damage to their other beliefs. However, the use of Materialism is inadequate for the explanation of phenomena of the universe, so that "no one would not see explanations of this kind to be completely inept."⁸¹ Theologians would have a problem with Materialism, because "the Materialist Evolutionists thought they had destroyed God."⁸²

The level of certitude for the thesis "Evolutionism is incompatible with Materialism" is at minimum at the level of the metaphysically certain. The proof is the principle of causality, that the effect cannot be greater than the cause. Further, the convergence of all of the above arguments are proof, especially the lack of the fulfillment of the principle of sufficient reason, since matter needs determining form. This agrees with the opinion of Palmes.⁸³ Calcagno also agrees to certitude.⁸⁴

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.⁸⁵ This is the method of Aristotle and St. Thomas.⁸⁶ The great achievement of Aristotle was to understand matter, which his predecessors, especially Parmenides and Heraclitus had a difficult time doing. Concerning this understanding of matter, not just in its obvious aspect of an entity experienced by the senses or by scientific instruments, but rather as substantially constitutive of all physical reality, natural reality, is one of the greatest achievements of the philosophic genius of Aristotle (Confer: Aristotle Physics; Aristotle Metaphysics).⁸⁷

In Evolutionism, is the philosophical understanding of matter essential? Evolution is a process of change. Aristotle presents matter as an essential element in the phenomenon of change, the phenomenon which so polemicized Parmenides and Heraclitus. According to Aristotle, in order to understand the phenomenon of motion there must be a potential principle, which takes from the material all that it is to become. In all changes between two opposite terms, there must exist a permanent subject for the change, so for change of place, something is first here and then there; in quantitative change something is greater or lesser; in qualitative change something can be healthy or sick; so in the same way substantial change (as in Evolutionism) must have something which is present in the process of generation or corruption (Aristotle Metaphysics 8. 1. 1042 a 30).⁸⁸

In Evolutionism, is the potency of matter merely static and passive in relation to the activity of form? Matter, in the technical definition of Aristotle and the Neo-Scholastics, denotes the potential element in being, potential and indeterminate, and in opposition to "form" which represents the element of determination and actualization. Note that the potency we treat here is not merely the possibility (potentia obiectiva) but is real potency (potentia subiectiva) and this potency penetrates to the very nature of being, whether in the genus of substance or accident.⁸⁹

In Evolutionism, is the real function of matter something that can be ignored or substituted? Material things are the very things generated and corrupted, according to Aristotle. So material has a function that cannot be substituted in the explanation of change. In fact, matter is the subject of becoming because it is the substratum which is generated and corrupted.(90)