What was thomas aquinas theory

He is, Thomas thinks, since God satisfies the condition for this appellation perfectly. This is the Eternal Law lex aeterna through which the divine intellect creatively designs and directs all creatures to a common end the common end of the universe , promulgating in time this eternal ordinance of His reason by the very act of creating beings and endowing them with spontaneous natural inclinations to move toward their own perfection in the context of the universe and its overall and unified perfection.

Created beings without intellect and will observe the eternal law, the eternal directives in the creative mind of God, spontaneously or automatically and perfectly. In the case of human beings, this eternal law directs them spontaneously toward their full and complete good by ordaining their essential nature to acts of understanding and desire for the goods constitutive of human perfection or fulfillment. But human beings have each their own intellect and will, so their spontaneous inclination and subsequent movement toward that full and complete good is brought about or not, since it can be resisted or rejected by conscious ratification and cooperation, that is, knowingly and willingly.

Thus, in the human world we have the Eternal Law as received and understood from the inside, as it were, and observed only conditionally: when humans correctly understand, desire, and act for the goods of human nature food, drink, clothing, shelter, creative activity, knowledge, friendship, etc. They are not making a law for themselves, but are discovering it and appropriating it for themselves. They are discovering and potentially ratifying in action the divine design-plan for their nature, to which non-rational creatures witness in whatever they do and undergo, although they are neither cognizant of this plan as law, nor capable of knowingly instantiating or resisting it.

The natural law, according to Aquinas, has certain basic and self-evident precepts or dictates, dictates knowable to any human with a properly functioning intellect and a modicum of experience of the world. The basic precepts of the natural law command human nature to seek obvious human goods; when the status of some presumptive object of human action as a good is less evident, investigation is required to determine its status.

Not all, however, are equally fit for this task of discernment about what is good for human nature in general and good for this particular human being as such. This natural law instantiating practical reasoning about what is best for humans by nature and therefore about what is ordained by God spontaneously and appropriately results, as Thomas observes, in the construction of man-made laws. Because of this inherent limitation of the human mind, humans must make their own laws to supplement that portion of the Eternal Law that they do spontaneously and readily grasp which portion includes the rudimentary parts of the natural law [15] , to direct themselves in community to their fulfillment.

The master principle of natural law, wrote Aquinas, was that "good is to be done and pursued and evil avoided. Reason, he taught, also enables humans to understand things that are evil such as adultery, suicide, and lying.

While natural law applied to all humans and was unchanging, human law could vary with time, place, and circumstance. Aquinas defined this last type of law as "an ordinance of reason for the common good" made and enforced by a ruler or government. He warned, however, that people were not bound to obey laws made by humans that conflicted with natural law. Aquinas asserted, "Yet it is natural for man, more than any other animal, to be a social and political animal, to live in a group.

Aquinas further observed that people tend to look only after their own self-interest. Thus, Aquinas did not agree with St. Augustine that the main purpose of government was simply to keep the sinful in line. Aquinas saw government as also helping to work for the "common good" that benefits all. The common good included such things as protecting life, preserving the state, and promoting the peace. Aristotle would have called this "the good life. Aquinas addressed the problem of unjust rulers who might be a king, the few rich, or the many poor.

Aquinas noted that when rulers make laws that violate natural law, they become "tyrants. What should the people do about a tyranny? Aquinas agreed with St. Augustine that the subjects of unjust rule are not obliged to obey the laws since they are not legitimate. But Aquinas went far beyond St. Augustine and virtually all other medieval thinkers on this matter. Aquinas argued that the subjects of a tyranny, acting as a "public authority," might rebel and depose it.

Aquinas cautioned that the people should not do this hastily, but only when the damage done by the tyranny exceeds what may occur in a rebellion. This was one of the first justifications for revolution in Western thought. Aquinas further developed the meaning of "just war" that had been discussed by the Roman statesman Cicero and by St. For a war to be just, there must be these three conditions:. A "just cause" for an attack on an enemy "because they deserve it on account of some fault" such as avenging wrongs they have committed.

A "rightful intention" to advance good or avoid evil such as punishing evil-doers and not simply grabbing land or goods. Aquinas wrote thoughtfully about the best form of government.

He, like Aristotle, preferred a mixture of government forms. Aquinas recognized the value of a king, "a shepherd seeking the common good of the multitude. The nobility, Aquinas argued, should advise the king and limit his power.

These were radical ideas for a time when kings claimed no one but God could hold them accountable. Aquinas spent his last years teaching and writing in Italy.

He died in at age 49 from an illness he developed while walking to France to attend a church conference. About 50 years after his death, however, the church revived his works and made him a saint. The writings of St. Thomas Aquinas combining reason and faith became the basis for official Roman Catholic doctrine known as "Thomism". In addition, his forward-looking political ideas regarding natural law, unjust rulers, and rebellion influenced European Enlightenment philosophers such as John Locke and even Americans such as Thomas Jefferson and Martin Luther King.

How did Aristotle and St. Augustine differ in their views about the natural world and government? How do you think the writings of St. Klosko, George. But, if Socrates is an animal he should be as subject to corruption as is any corporeal substance, and as subject to death as any animal.

Here it is important to make an initial distinction. As we've seen, living things act to preserve their existence through their vital activities, and succeed in doing so for a time, even if they eventually succumb to the reaper. So we may say they are naturally subject to death because of their composed corporeal natures.

And yet, it does not follow that they must corrupt and die; by and large their lives consist in preventing the corruption to which they are subject. This fact alone shows that there are causes with the power to fend off death, even if not to fend it off permanently. However, it is then at least possible that some other cause, a cause with much greater power than the natural causes of living things possess, could fend off death for them without end and preserve them alive without end.

The obvious candidate for this cause is God by miraculous intervention; if living things have limited power to fend off their own deaths, presumably God has unlimited power to do so for them. So what is corruptible by nature may not in fact corrupt. While animals are naturally subject to death, they could be supernaturally immortal. So also even if human beings are naturally subject to death, it may well be within the power of God to keep them from dying by a preternatural gift. This condition of having been given a preternatural gift preserving them from death would be the condition of the first human beings in the biblical account of Eden, the preternatural gift lost by Original Sin through which death entered into the world, however else one understands those data of revelation.

But philosophically we can say no more of them than that human beings are naturally subject to death but need not die.

However, the world we live in is not an Edenic paradise into which death has not entered. Living things die. Human beings die. Socrates died. On the other hand, according to Thomas, Socrates' soul is incorruptible where the souls of other animals are not. It is not even naturally subject to death by corruption. Is there a possibility for immortality, particularly personal immortality, here in the incorruptibility of Socrates' soul?

One might be tempted to say yes. One might say that in the first place the incorruptible soul of Socrates looks like a person in the current sense of that term.

It is a thinking or conscious thing, since it is clearly a thing at least in the sense of a subsistent, and it has the power of intellect, even if it has no other conscious cognitive powers of the animal for which it formally was a soul. What person? Well Socrates was a person in that very sense as well, although he had more conscious cognitive capacities than does his soul after death.

It seems incongruous to suggest that we have two persons—Socrates and Socrates' soul. After all that would seem to strike against the unity Thomas was at pains to maintain. While Socrates was alive, were these two persons present? There is but one person, and it is Socrates. But then upon the death of Socrates, what happens? Does the person who is Socrates cease to exist, and a new person that is Socrates' soul come to exist? But, it seems much easier and simpler to say that upon Socrates' death the person that was Socrates survives as Socrates's soul.

Before death Socrates was composed of a soul and a body. After death he is composed simply of a soul. If we hold that position then, because of the incorruptibility of the soul, while the animal that Socrates was dies, the soul that Socrates becomes survives, and thus Socrates himself is immortal, and not subject to death, not subject to death even by nature as the animal is.

Socrates is simply immortal. However as an interpretation of Thomas this approach will suffer several severe difficulties. First, on its own terms it is hard to avoid the conclusion that before Socrates' death, there are two persons present. It was that the intellectual soul as such is a particular thing and subsistent, and that includes while it is the soul of a living thing.

So if we are going to take the recent minimalist account of person that the term expresses in this proposed interpretation, a thinking or conscious thing , then we have the person that is the particular and subsistent thing that is the soul before the death of Socrates. But Thomas thinks Socrates thinks, and is thus a thinking thing. So we also have the person Socrates. Is the person that is the soul identical to the person that is Socrates? It seems not, given the argument of So this interpretation suggests that even if after death there is only one person, Socrates, before death there are two persons, Socrates and Socrates' soul.

In the second place, this interpretation explicitly relies upon an equivocation on the term 'person'. Thomas accepts from Boethius the definition of a person as an individual substance of a rational nature. Summa Theologiae IIIa.

It does not have a nature, but is one of the principles of a corporeal nature along with matter. And when we do so speak, what is meant is that its nature is to be the substantial form of an animal. Again, that is why it is not an angel. So strictly speaking, the human soul, even as a subsistent, is not and cannot be a person, unless one equivocates on the term, and in so doing abandons the Philosophy of Nature and Metaphysics within which Thomas thinks.

In the third place, this interpretation would make hay of Thomas' argument in There Thomas relied upon the vital activities of Socrates to make that argument--Socrates has vital activities that the soul does not possess as a subject or subsistent. But they are Socrates' activities as agent just as much as is the operation of intellect. The powers that those activities manifest are powers of Socrates in just the way the power of intellect is. So if one were to ask which of the powers might be thought to be not quite Socrates' power in the full sense, one ought to opt for the intellect, not the vital powers of the living body, since it seems that intellect belongs to something other that Socrates and is at best shared with Socrates.

But then why would Socrates become identical to the subject in virtue of a power that is not quite his, rather than cease to be with the powers that are properly his? Such questions, and the answers one might give to them, are again senseless if we situate what Thomas thinks back in what he wrote. The reason that intellectual power is no less Socrates' power than it is the soul's is because the act of being of Socrates is the act of being of his soul.

It is a mistake to think that because Socrates is not identical to his soul, his soul forms some other being with which he would share some power. Again, this has to do with the soul being his substantial form.

In the fourth place, this interpretation would suggest, in Thomas' terms, that the body with its powers is per accidens related to Socrates' being. If Socrates is a substance, and the body is per accidens to his being, then the body is per accidens to his substance. In which case he is not a corporeal substance or animal at all, even in this life.

The interpretation seems to return to giving the appearance that the intellectual soul is a kind of angel, only now adding that this angel is Socrates for a time associated with bodily powers. But recall Thomas' rejection of the Plurality of Substantial Forms position. His own account of the soul is that the animal powers of the soul are as much powers of the human soul as is the intellectual power—they are all powers in the second mode of per se predication.

In that respect they are all alike, and the human soul is thus per se the substantial form of a living body, not per accidens , and the person Socrates is that living body. When that living body ceases to exist through death, so also does the person who is Socratres. Finally, Thomas clearly understands and accepts the implications of his view that Socrates is the living animal, namely, that the continued existence of the human soul after death is not sufficient for the continued existence of the human person.

If the living animal no longer exists after death, then neither does Socrates. If the living animal is not immortal, then neither is Socrates. Consider these objections that Thomas himself considers. There is no resurrection of the body; only the souls of Abraham, Isaac, and Jacob live after death. Thomas writes in response that the soul of Abraham is not Abraham, and the life of Abraham's soul is not sufficient for the life of Abraham.

The whole composite of Abraham's soul and body must live for Abraham to live. Thus if only Abraham's soul lives after death, Abraham does not. Summa Theologiae Of course Thomas does not think that the resurrection of the body is demonstrable in philosophy. For him it is a revealed truth, not one of the praeambula fidei. Earlier we saw how Thomas' use of philosophical analysis helped to avoid the potentially distorting view of the theologian upon the nature of the soul.

Here, we see how a revealed truth helps the philosopher avoid an equally distorting philosophical account of the soul and personal identity that would skew the philosophical books toward a personal human immortality without having to live as a human animal.

When Aristotle rejected the Platonic Ideas or Forms, accepting some of the arguments against them that Plato himself had devised in the Parmenides , he did not thereby reject the notion that the telos of philosophical enquiry is a wisdom which turns on what man can know of God.

The magnificent panorama provided at the beginning of the Metaphysics as gloss on the claim that all men naturally desire to know rises to and culminates in the conception of wisdom as knowledge of all things in their ultimate or first causes. For much of the twentieth century, Aristotelian studies had been conducted under the influence of Werner Jaeger's evolutionary hypothesis.

On this view, Aristotle began as an ardent Platonist for whom the really real lay beyond sensible reality. With maturity, however, came the sober Macedonian empiricism which trained its attention on the things of this world and eschewed all efforts to transcend it. As for the Metaphysics , Jaeger saw it as an amalgam of both theories. The passage just alluded to at the beginning of the work is ascribed to the Platonic phase. Other passages have a far more modest understanding of the range and point of a science over and above natural philosophy and mathematics.

Platonice loquendo , there are entities which exist separately from sensible things and they constitute the object of the higher science. The more sober view finds a role for a science beyond natural philosophy and mathematics, but it will deal with things those particular sciences leave unattended, e. But these tasks do not call for, and do not imply, a range of beings over and above sensible things.

Jaeger found both these conceptions of metaphysics juxtaposed in a crucial passage of Book Six. Jaeger invites us to see here a monument to a lost hope and an abiding reluctance to bid it a definitive farewell. Aristotle mentions the possibility of an immovable substance, something existing apart from the natural realm. Without such a separate substance, natural philosophy will be first philosophy. If there is such a substance, it will be a kind of being different from material being.

The science that studies it will bear on a certain kind of being, immovable substance, immaterial being, not on being as being. It will be a special, not a universal, science. Jaeger sees Aristotle seeking to glue on to the special science the tasks that belong to a universal science, to make a theology into an ontology. Jaeger's hypothesis dominated interpretations of the Metaphysics until very recently.

Giovanni Reale's book had to await English translation before it could have any impact in English circles of interpretation. By that time, people were turning from Jaeger's account and toward a more direct reading of Aristotle. When we reconsider Thomas as a commentator on the Metaphysics , it becomes clear that his reading is in stark opposition to Jaeger's claims.

But let us first lay out Thomas's view of metaphysics. His question is Aristotle's: is there any science beyond natural science and mathematics? If to be and to be material are identical, then the science of being as being will be identical with the science of material being. That is what Aristotle rejects in the passage just quoted. It is in the course of doing natural philosophy that one gains certain knowledge that not everything that is is material.

At the end of the Physics , Aristotle argues from the nature of moved movers that they require a first unmoved mover. If successful, this proof establishes that there is a first mover of all moved movers which is not itself material.

Furthermore, the discussion of intellect in On the Soul III , to which we alluded in the preceding paragraph, points beyond the material world. If the activity of intellect provides a basis for saying that, while the human soul is the substantial form of the body, it can exist apart from the body, that is, survive death, it is an immaterial existent. The Prime Mover and the immortal souls of human beings entail that to be and to be material are not identical. Since these are acquisitions at the limit of natural philosophy, they represent possible objects of inquiry in their own right.

This is pre-eminently the case with the Prime Mover. It seems inevitable that there should be a discipline whose principal aim is to know more about the divine. How can it be described? Thomas discusses early the way theoretical sciences are distinguished from one another in the course of his exposition of the tractate of Boethius On the Trinity. The text speaks of three kinds of theoretical science, physics, mathematics and theology, and Thomas invokes the methodology of the Posterior Analytics.

A scientia is constituted by a demonstrative syllogism. From a formal point of view, a conclusion follows necessarily from the premises in a well-formed syllogism. Still the conclusion may state a merely contingent truth. What is needed in a demonstrative syllogism is not just the necessity of the consequence but a necessary consequent, and this requires that the premises express necessary truths. That which is necessary cannot be otherwise than as it is; it cannot change. Science thus requires that it bear on immobile things.

There is another requirement of the object of speculative or theoretical knowledge which stems from intellection. The activity of the mind, as has been mentioned, is not a material event; it is immaterial. Since it is the mind that knows, science is a mode of its knowing, and will share its nature. Thomas thus states two essential characteristics of the object of speculation, the speculabile : it must be removed both from matter and from motion.

If that is the case then insofar as there are formally different ways in which speculabilia can be removed from matter and motion, there will be formally different speculative sciences. By this analysis, Thomas has provided the necessary background for understanding the text of Boethius but also more importantly that of Aristotle as it is developed in the chapter from which Werner Jaeger quoted in order to display the failure of the Aristotelian project. Of things defined, i.

And these differ because snub is bound up with matter for what is snub is a concave nose , while concavity is independent of perceptible matter. This makes it clear that the way in which natural things are separated from sensible matter is the way in which the definition common to many things abstracts from the singular characteristics of each.

But it is the matter as singular that is the principle of change in things, so the common definition has the requisite necessity for science. This or that man comes to be, but what-it-is-to-be-a-man does not come to be or pass away.

Lines, points, numbers, triangles—these do not have sensible qualities whether stated universally or singularly. The fact that we define mathematicals without sensible matter does not commit us to the view that mathematicals actually exist apart from sensible matter. In the commentary on Boethius to which reference has been made, Thomas has early on recalled another fundamental aspect of Aristotle's thought. The objects of thought are either simple or complex, where complex means that one thing is affirmed or denied of another.

Knowledge of simples is expressed in a definition, that of the complex in a proposition. Thinking of human nature without thinking of singular characters of this man or that is a matter of definition, not of assertion, as if one were denying that human nature is found in singular matter.

So too defining mathematicals without sensible matter is not tantamount to the judgment that mathematicals exist apart from sensible matter. These are both instances of abstraction, where abstraction means to think apart what does not exist apart. Thus it is that the question of metaphysics turns on what Thomas calls separatio. To separate differs from abstraction in this that separation is expressed in a negative judgment, an asserted proposition: this is not that, that this exists apart from that.

The relevant separation for metaphysics is the negative judgment that to be and to be material are not the same. That is, there are things which exist apart from matter and motion—not just are defined without, but exist without matter and motion. What then is the subject of metaphysics? The discussion of definition in effect bore on the middle terms of demonstrative syllogisms. The suggestion is that formally different modes of defining, with respect to removal from matter and motion, ground the formal difference between types of theoretical science.

The subject of a demonstration in natural philosophy is defined without singular but with common or universal sensible matter; the subject of a mathematical demonstration is defined without any sensible matter.

How can the subject of metaphysics be expressed? The possibility of the science depends on our knowing that some things exist apart from matter and motion. Mathematics does not presuppose the separate existence of its objects; metaphysics does. Why not then say that metaphysics deals with things separated from matter and motion, that is with a particular kind of being? But that is not the subject ever assigned to this effort by Aristotle.

The methodological reasons can be found in chapter 17 of Book Seven of the Metaphysics : the subject of a science must always be a complex. That is why the subject of this discipline is being as being. Why should we say that, in our desire to learn more about separate substances, we should take as our subject all the things that are? The short answer is this: in order to be a theology, metaphysics must first be an ontology. Separate substance, divine being, is not directly accessible for our inspection or study.

We come upon our first secure knowledge of a god in the proof of the Prime Mover. Tantalizingly, once seen as a necessary requirement for there being any moved movers, the Prime Mover does not become a thematic object of inquiry in natural philosophy. One obvious reason for this is that such an entity is not an instance of the things which fall under the scope of the science. Knowledge of it comes about obliquely and indirectly.

The same restriction is operative when the philosopher turns his culminating attention to a deity. How can he know more about the first cause of things? If the Prime Mover is known through moved movers as his effects, any further knowledge of him must be through his effects.

It is by describing the effect as widely as possible that one seeks to come to a knowledge of the first cause unrestricted by the characteristics of mobile things.

That characterization is being as being. The subject of metaphysics is being in all its amplitude in order to acquire a knowledge of the cause of being that will be correspondingly unbounded.

Earlier we indicated the difference between philosophy and theology in the writings of St. That distinction takes theology to mean discourse that takes its rise from the revealed truths of the Bible. But there is also a theology which constitutes the defining telos of philosophical inquiry. In the following passage, Thomas contrasts the two theologies in a way which throws light on what was said in the preceding paragraph.

Philosophical theology is not some science distinct from metaphysics; it is simply the name that can be given to metaphysics because it appeals to a god as the cause of its subject. This may make it seem that knowledge of a god is merely a bonus, a tangential consideration; on the contrary, it is the chief aim of the science. But the divine can only be known indirectly, through its effects.

For this reason, metaphysics can be viewed as an extended effort to examine substance in order to come to knowledge of the first cause. And given the principle that we name things as we know them ST Ia. Thomas says that the truth of the proposition a god exists is knowable in itself, because the predicate is included in the essence of the subject. But it is not knowable to us, because the essence of a god is unknowable to us.

He also says that the essence of a god is existence, that such a being is ipsum esse subsistens , and yet that we cannot know this essence. How is any of this coherent? Mustn't one know what one is talking about to deny anything of it, in particular to deny that it is knowable to us? How can Thomas simultaneously assert what the essence of a god is and deny that we know it?

In order to understand why his claims about the existence and essence of a god are not incoherent, we need to place them within the context of Aristotle's Posterior Analytics.

According to Aristotle, one mode of per se predication, the first, is that in which the predicate of the proposition is included within the definition of the subject. We've already seen the second, where the subject is included in the defintion of the predicate, the mode appropriate to the powers of a subject.

So in the first mode, if one immediately knew the essential definition of the subject, one would immediately know that a particular proposition is per se true simply by knowing that its predicate is included within that essential definition. Any proposition in which the predicate is included in the essential definition of the subject is knowable in itself.

For instance, Thomas thinks that anyone who knows the language will know the truth of a proposition like a whole consists of the sum of its parts. Because the terms are related in this fashion and so fundamental in the language, no special knowledge is necessary to grasp its truth. Such a proposition is thus knowable in itself but also to us.

However, clearly this account leaves open the possibility of subjects in which the essential definition is either unknown or even unknowable. For instance, if we suppose that H2O is the essential definition of water, we have to recognize that there will be many who will not know it. So that water is H2O will be knowable in itself, even if unknowable to us, until we engage in Chemistry.

Consider the mind. Clearly we use the term 'mind' meaningfully in any number of sentences. But perhaps, as Colin McGinn has argued, the actual nature of mind is incomprehensible to limited minds such as ours.

In that case it might be knowable in itself, and yet strictly unknowable to us. Thus the distinction between what is knowable in itself and what is knowable to us is not incoherent.

What of the claims that the essence of a god is not just unknown to us, but unknowable to us, that the essence of a god is His existence, and that it is ipsum esse subsistens? Don't these remain jointly inconsistent and thus incoherent, even if the underlying distinction is not?

In claiming that the essence of a god is not knowable to us, Thomas is talking about its accessibility to philosophical inquiry. The human mind of itself is proportioned to knowing material things. It can only know immaterial things insofar as causal arguments can be made to posit the existence of such things as necessary to the explanation of material things—causes that are only appealed to when one has excluded the possibility of a material explanation of the phenomenon. But we've already seen that to claim that something is immaterial is not to know any property of it, much less its essence.

Still, it remains available to Thomas to claim that while the knowledge of the essence of a god is unknowable to philosophy, it is known to us by Revelation. Indeed, he appeals to God's revelation to Moses on Sinai to establish the claim that God's essence is ipsum esse subsistens —that is to say, the being who reveals Himself to Moses identifies Himself as what the philosophers are looking for but cannot find in its essence.

Summa theologiae Ia. It is not something that can be known by both Revelation and Philosophy. So the essence of God is knowable in itself, and also to the learned.

But the learned are not the philosophers. Rather they are all those who know it by faith in God's revelation. So, can the existence of God be philosophically demonstrated? If God's essence is His existence, and His essence remains in principle philosophically unknowable to us, how could it be demonstrated?

In fact, Aquinas claims that it can be demonstrated that there is a god, and that there is only one god.

That God's essence remains in principle philosophically unknowable to us is the basis for Aquinas' denial that the existence of God can be demonstrated a priori. And any reliance upon knowledge of the essence that is only known to us by faith would by that fact cease to be properly philosophical.

However, we have seen that Aquinas relies upon the distinction between nominal definitions of terms and essential definitions of the subjects referred to by those terms. To demonstrate the existence of a god one may use nominal definitions that appeal to a god as the cause of various phenomena. This is to argue a posteriori. Again, some will claim that Aquinas isn't really interested in proving the existence of God in these Five Ways.

After all, he already knows the existence of God by faith, and he is writing a theological work for beginners. What need is there of proving the existence of something he already knows exists?

The Ways are very sketchy, and don't even necessarily conclude to a single being, much less God or the Christian God. In addition, Aquinas claims that God's essence is his existence and that we cannot know His essence, so we cannot know His existence. Aquinas must really intend the Five Ways as less than proofs; they are more like incomplete propaedeutic considerations for thinking adequately about God in Sacred Theology. In effect, Aquinas doesn't think philosophy can in fact demonstrate the existence of God.

But as elsewhere these claims are ambiguous and suffer at the hands of Thomas' own texts. In the first place, the objection that he already knows by faith that God exists has some merit in it, if we understand it as directed at a reading of Thomas that would have him attempting a foundational enterprise of grounding religious faith in what is rationally demonstrable by Philosophy. But that reading is anachronistic, and does not attend to the context of the Summa Theologiae.

There is no reason to think that Thomas thinks the proofs are necessary for the rationality of religious faith. They are part of the enterprise of showing that Sacra Doctrina meets the condition of a science as described by Aristotle in the Posterior Analytics , which he had argued in the first question of the Summa , an issue that is different from the question of the broad rationality of religious faith.

He cites Aristotle's distinction between demonstrating the existence of some subject, and going on to demonstrate properties of that subject by appeal to the essence of the subject as cause of those properties. The first kind of demonstration is called demonstration quia , the second demonstration propter quid. In order to have any science at all, the subject matter must exist. So demonstration quia must precede demonstration propter quid.

If you want to have a science of unicorns, you have to show me that there is at least one unicorn to be studied. There is no science of what does not exist. So there are two demonstrative stages in any science, the demonstration of the existence of the subject quia , and the demonstration of the properties of the subject through its essence propter quid.

Aquinas' denial that the essence of God can be known philosophically is a denial that one can have propter quid scientific understanding of a god through philosophy.

It is not a denial that there can be demonstration quia of the existence of a god. There is no reason to deny that Thomas thinks the Five Ways are proofs or demonstrations in the most robust sense, namely that which he appeals to as set out by Aristotle in the Posterior Analytics.

One source of the ambiguity in the objections comes about because it is claimed that Aquinas does not think one can demonstrate the existence of God. But in terms of the Posterior Analytics one cannot demonstrate the existence of anything under a proper name. One can only demonstrate in the relevant sense using common nouns, since such nouns are the only ones that have definitions, either nominal or essential. So strictly speaking it is true that Thomas doesn't think one can demonstrate the existence of God in the Five Ways.

It is for that reason that Thomas himself thinks one must actually argue additionally that a god must be utterly unique, and thus that there can be only one, which he does several questions after the Five Ways Summa Theologiae Ia. It is the utter uniqueness and singularity of a god that undermines the objection that whatever the philosophical arguments terminate in, it is not the god of Judaism, Christianity, and Islam, a god who is only known by faith.

That is simply to deny Thomas' claim that the god Jews, Christians, and Muslims believe in can be known, but only partially by philosophical analysis. If the demonstrations work, as Thomas thinks they do, what other god would the Jews, Christians, and Muslims believe in? There is no other god. Given God's revelation, He must be identified with the utterly unique being the philosopher's argument terminates in.

Finally, the sketchy character of the Ways reflects the fact that they are directed at beginning students. However the audience of beginners that Thomas has in mind are not beginners in Philosophy.

They are beginners in Sacra Doctrina. As we have seen, in the medieval educational setting such beginners would be thoroughly steeped in the philosophical disciplines before ever being allowed to study Sacra Doctrina. So Aquinas could expect his readers to know the much more extensive and complete arguments he was gesturing at with the Five Ways, arguments to be found in detail in other figures like Aristotle, Avicenna, and so on, as well as in other works of his own, the Summa Contra Gentiles for example.

In short, even if the Five Ways are judged to be unsound demonstrations, a judgment that requires close analysis and examination of the filled out arguments, there is no reason to suggest that Thomas took them any less seriously as demonstrations or proofs in the fullest sense. Now, even though there can be no demonstration propter quid of God's essence or nature, this does not mean that philosophical theology is left with a bare knowledge of the existence of God, and nothing more.

However, recognizing that the way in which God possesses these perfections must be different from the way in which creatures possess them, one must deny that God has them in the creaturely mode. So, while on the basis of effect to cause arguments we can say that God is just, wise, good, perfect, and so on, we do not know what it is for God to be just, wise, good, and perfect.

We end up denying of God the creaturely mode of these perfections. In this way God is approached negatively by denying things of Him rather than by directly knowing what God is.