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Philosophy of Evolution: For Human Body

The Level of Certitude


The evolution of the human body  is possible.

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.52 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.53 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.54 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.55

Certitude could arise from some observable fact or experiment. However, there is no experiment to prove evolution.56 However, some restricted observation of evolution of the body of man is possible within the species.57 Such observation had been done by the study of the fossil record and morphology, but La Vecchia believes that such a study should be done in the opposite direction, back to the origins of material culture.58 The researcher should look for observable evidence of hominization in the development of tools and pottery, in funeral burials and the remains of respect, and evidence of art.59

Certitude could arise from some philosophical explanation that exists, which applies general evolution to the body of man. Explanations were given by several Neo-Scholastics: Klubertanz from equivocal causality, chance and Providence,60 and La Vecchia on the predisposition of Prehominids up to Hominids.61

Certitude could arise if the argumentation was based on some philosophical principles. Although the evolutionary development of the body of man needs a cause, "the special causality of God in the origin of man’s body need not be an immediate one."62 Further, since the body of man is material, the evolution of the material world would seem to be a sufficient reason for the eventual origin of the body of man.63

Certitude could arise if the explanation is sufficient, due to the principle of sufficient reason. But the explanation of Klubertanz appears to be sufficient when "at the instant when the proper material dispositions are present in this being, God would create in the matter thus essentially disposed a human soul, in the same way in which He creates the soul in the course of normal human generation."64 Also, there does not seem to be any sufficient reason why material evolution stop just prior to the origin of the material human body.

Certitude could arise if the explanation was rooted in St. Thomas Aquinas, thereby being faithful to tradition. The explanation is rooted in Aristotle and St. Thomas Aquinas. St. Thomas reprises Aristotle who taught that "nature proceeds little by little from things lifeless to animal life" and "there is observed in plants a continuous scale of ascent toward the animal."65 This observation of natural ascent is helpful to understand the evolutionary progress toward the human body.66 St. Thomas notes, "...less noble creatures are in the service of the more noble...Further, every creature is in the 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).67

Certitude could arise if Neo-Scholastics agree on the possibility of the evolution of the body of man. Prominent Neo-Scholastics who agree on the philosophical possibility of the evolution of the body of man are: Nogar,68 Klubertanz,69 Benignus,70 and La Vecchia.71

Certitude could arise due to recent scientific confirmation by convergent scientific arguments. Benignus states that "St. Thomas’ answer ( that primary matter is appetite or urge to live and ultimately to live on the highest possible level, that is to say, as the body of man) and the answer of science are in no way in conflict or disagreement; indeed, they amount to the same thing..."72 Bittle states: "The dissent of man from brute ancestry is on purely scientific and philosophic grounds, a tenable but doubtful theory."73 Facchini noted "...the physical conditions necessary (fit environment, development of the brain), with particular reference to the Australopithecines, among which the lineage that brought to the human beings can be individuated...These are arguments to consider that documents of cultural behavior are already found with Homo habilis. They become more evident with Homo erectus and above all with Homo sapiens."74

Certitude could arise if the opposite opinion is not tenable, but Klubertanz notes, "It (evolution of the human body by equivocal causality) is certainly not the only way in which man could have come to be."75 However, Productionism, the production of the body of man by God from pre-existing material, unnecessarily diminishes the use of secondary causes. "Unnecessary" is mentioned because the matter of the body is pre-existing. "Necessity" does occur in the case of the immaterial soul of man, since it is necessary for God to create an entity that is not material and is not intrinsically dependent on material. Further, according to St. Thomas (Aquinas Summa Contra Gentiles 3. 22), matter already has an appetite to be in service of the higher forms of life, so that Productionism would unnecessarily seem to duplicate the already established plan of God.

Certitude could arise if the objections of adversaries are able to be answered. But the objections of the adversaries in general are the same general objections to evolution itself, which have already been answered. The specific objection to the evolution of the body of man is that man is essentially different than the other animals, and this is due to man’s rational soul. However, this does not directly touch the evolution of the body of man; and all Neo-Scholastics have always maintained the direct and immediate creation of the subsistent soul of man. Again, Di Napoli76 notes that evolution of the body of man would be impossible if some philosopher held, the eternity of material, or the spontaneous generation of life, or the identity of the monkey and man, or mechanistical transformation without finality and without the influx of God; but here in this argument for the evolution of the body of man, none of these issues is proposed. Later, the spontaneous generation of life will be considered, but the matter makes no difference here, in the treatment of the origin of the body of man.

Certitude can be had from the possibility of philosophers and theologians admitting this mode of origin without damage to their other beliefs. Klubertanz notes, "The possibility of this mode of origin can be admitted by both philosopher and theologian," although he notes later, "There are some theological problems involved in such an admission...competent theologians think these problems can be solved; at any rate, a difficulty in itself does not constitute a refutation."77 The theologian can accept the evolution of the body of man, since this fits the recent schema proposed by Marcozzi, who said God’s intervention is necessary and evident at "the coming of man," because God directly and immediately creates the soul of man.78 Palmes quotes the encyclical of Pope Pius XII, Humani Generis, which explicitly states that the pope does "not prohibit" the doctrine of evolution in so far as "inquiring about the origin of the human body from already exiting and living material."79

Certitude can be had from the fact that evolution is the best answer now for the origin of the human body.80 St. Thomas makes a distinction between a "verified" universal (dici de omni) and a "provisional" universal (ut nunc).81 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 of the body of man is the best answer we have now.82

The level of certitude for "Possibly, the human body has evolved" is at minimum at the level of possible. Given the assembled proofs and their convergence, the proposition of the evolution of the human body may be even philosophically probable. The major proof is the principle of secondary causality. 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 Klubertanz who says, "It seems possible that the human body itself could take its rise in this does not seem to be impossible."83 Bittle, in 1945, notes: "As a working hypothesis, the descent of man through evolution, if we exempt man’s soul, is tenable, but the fact itself has not been proved."84 Di Napoli says the evolutionary origin of the body of man is philosophically "not impossible."85 In fact, given more biological arguments (Di Napoli is writing in 1954), Di Napoli would even be willing to say the propositon of the evolution of the body of man is "probable."86

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.87 This is the method of Aristotle and St. Thomas.88 This view is confirmed by the Neo-Scholastic Karl Rahner who argues for the importance and dignity of the material body of man.89 However, Facchini notes that, "The moment of the appearance of Man in the history of life is an event that is not easy to be individualized. When, where, and how the human threshold has been reached is still now a topic of interpretations and hypothesis."90 Further, Klubertanz notes that no realistic philosophy can be complete, unless it includes a philosophy of nature; and it is in the area of the philosophy of human nature where most of the problems occur in philosophy of nature.91

Author:  John Edward Mulvihill, S.T.D., D.Min., Ph.D.
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