The proofs of the existence of God The philosophical theism or the affirmation of God as First Cause of the being of entities was the main issue of Christian philosophy, along with the existential unity of the human person and the intellectual validity of the access to being – or realistic noetics. The development of the proofs of the existence of God was already a classic issue when thomistic systematisation collected a large part of the previous Christian philosophical heritage. 

Following Plato’s thought, St. Augustine explicitely formulates the rational access to God through three ways: the proof of eternal truths, the proof of desire for happiness and the socalled deontological argument. In the proof of eternal truths, St. Augustine states that certain truths have necessity, immutability and eternity, features that they have regardless of contingent beings. 

These necessary truths are previous to the existence of contingent beings and can not rely on them; therefore, they must rely on the existence of a necessary Substance. Detractors of this proof claim, justifiably, that it lacks demonstrative value, for necessity and eternity can not be placed in the same order. 

The argument reaches God in an ideal order, from eternal truths and by inner necessity, and doesn’t descend into its real noetic basis in being as such. There is, then, an illegitimate step from the ideal towards the real. The augustinian proof of the existence of God by the desire for happiness is also known as the eudemonological argument: every natural desire implies the real existence of what is desired; since man has desire for God by natural need, God must exist. It is also necessary here to refuse the apodictic demonstration of the existence of God from the desire for happiness. 

On one hand, it is not true that every desire implies the existence of what is desired and, on the other, it is also incorrect that man naturally feels desire for God but, in any case, man feels desire for good in general. Finally, the deontological argument tries to find out if one can correctly understand the existence of God as supreme Legislator from the knowledge of the natural moral law. 

The argument proceeds as it follows: in human nature there is a knowledge of a natural moral law. This law is necessarily caused, and proceeding towards infinite in the series of legislator causes is impossible; therefore, the existence of a first legislator cause must be accepted, which corresponds to the nominal definition of God. 

We call natural law to any necessary and immutable relation given between the natures of things; but this law aquires in man a special classification, for his will aims to universal good and is free from partial goods. The starting point of this proof is correct: the existence of a natural moral law is evident forehand of any demonstration.

Let’s focus now on the very raison d’ être of this moral law. Natural law has the efficacy of ultimate foundation of any legislation, but it does not have its own foundation itself. The natural law - guideline of human acts - is rational, altough it is not a product of reason; human nature is the support of this natural law, but not its cause. 

Natural law manifests as something given to human nature. If the intellect is given, the tendency of will towards good is given, the subordination of partial goods to general goods is given, all this clearly shows that natural moral is given to man by another one. Hence, we must accept the existence of a first Lawgiver cause, which we call eternal law. Aside this last proof, it is clear that the access ways to God proposed by St. Augustine follow a platonic orientation that often verifies an illegitimate transition from the ideal to reality. 

Our understanding of the divine essence is not previous to that of its existence. The socalled ontological argument has been developed in diverse ways, being that of St. Anselm the most renowned one. It reads as follows: In the ontological argument - in almost all its varitions – both the ontological basis and its noetic foundation fail. 

The ontological basis fails because it doesn’t caution that the idea of God is an idea abstracted from sensible things, while the noetic foundation fails because the ontological argument tries to use the principle of non-contradiction as a sole principle, when attributing real essence and existence to an ideal being is contradictory. 

The biggest possible devised entity only requires ideal existence, but we can not attribute a real existence to it without contradiction. Until then, most formulations had been philosophically expressed through concepts derivated from platonism. 

St. Thomas assimilated aristotelism to be used by the faith on creation. The possibility of the proof of God is solved by Aquinas by using demonstrations which have their starting point in the being of sensible realities to inductively proceed in search of their own cause. 

All thomistic ways have four key elements: the starting point – which is a universal effect evident in singular beings in all of them – the principle of efficient causality, the principle of the impossibility of a process towards infinite and the final end of the way, which is always the existence of the First Cause. 

The first way starts from the existence of movement, the second one from the subordination of causes, the third from the contingency of beings, the fourth from the grading of perfections and the fifth from the ordering towards an end. 

Each way formulates the principle of causality in the manner that best suits the formality of its starting point. 

In the first one, everything that moves is moved by another; in the second one, every subordinated cause is caused by another; in the third one, the contingent being is caused by a necessary being; in the fourth one, every graded perfection is participated and, therefore, caused; in the fifth one, the ordering towards an end is caused. 

The impossibility of infinite in causal series – in fact and essentially subordinated – can be noticed in each way. And finally, the conclusions of these ways end in the need of God as Unmoved Mover, non-caused Cause, Highest entity and Supreme ruler of the Universe.

The first way starts from the existence of movement, the second one from the subordination of causes, the third from the contingency of beings, the fourth from the grading of perfections and the fifth from the ordering towards an end. 

The third way starts with the being of beings which are possible to being and to not-being, i.e., beings that, while existant in act, are indifferent for being and not-being. Such indifference is evident in their generation and corruption. The starting point is, then, the finite being as something limited in duration. 

The being limited in duration – that is to say, contingent – is caused by a necessary being. If everything is possible of not-being, then nothing existed once, but this is not true since, then, anything would exist now. Therefore, a necessary being must exist. It is not possible proceeding towards infinite in the series of those necessary beings which have the cause of their necessity in another one. It is not about the causes of movement now, like we saw in the first way; nor about the activity, like in the second one, but about the causes of being. 

There is a being for itself, not subordinated to any other else, neither in the movement, in the causation nor in being. The being Necessary by itself doesn’t have existence, but it is its existence itself. It is the ipsum subsistens. 

The fourth way focuses on participations or gadations. The starting point is the observation that certain perfections realised in diverse grades exist in things, like the essential or the especific ones. Those perfections not realised in grades must be excluded; furthermore,

St. Thomas doesn’t take into account all perfections, but only those of truth, goodness and nobleness. In our experience, we find things with greater or lesser entity, unity, truth, etc. The pure transcendental perfections wich appear participated in things are received by subjects, i.e., are effectuated and, for this reason, caused by something external. 

A perfection is possessed in a greater or lesser degree in conformity with its proximity or remoteness from the source from which it comes. In short, limited perfections are always participated. And we can not proceed towards infinite, but rather to conclude in the existence of something Maximum in perfection. 

Only the Maximum entity is by essence, all other beings exist by participation. There exists then a Maximum entity which causes being, goodness and any other perfection of things, since in God we find the absolute identification of its existence and its essence. 

The fifth way starts from the dynamic finite being, but not in the formality of movement or activity, but in that of the direction or ordination towards an end. Every moved’s movement has a direction towards an end. There is certainly an ordination towards an end in the activity of living beings; this is evident since they act in the same way and all tend towards what is good for them. There is a relation between the agent, its action and the end of this action. Chance, then, must be excluded.

The direction or ordination towards an end of the movement or operations of living beings is efficiently caused by an intelligent being. When we deal with Natural Science, we don’t look further than immediante causes, and every fact is explained by the nature of the being from which it comes from. But, when dealing with metaphysics, we are asking for the first cause and its first principle. We must demonstrate that the direction towards an end is caused, not by the nature of the being to move, but by someone else. 

We have either beings that don’t have rational knowledge and others that move towards their end by themselves. But all agents need to be directed by something that knows the reason of that end. It is curious that neither the human act, regarding this ordination to an end, can be explained in all its metaphysical range by just appealing to freedom, for the question here is who is directing the knowledge towards its respective object, so that also those acts of beings gifted with knowledge are claiming fom an intelligent being which explains their ordination. 

We can not proceed towards infinite in the series of intelligent beings, but we’ll have to reach an intelligent being whose acts don’t need to be regulated by anybody. The way concludes in a highly intelligent being, Supreme ruler of all movements, actions and operations of all natural beings. In all ways, the starting point has a physical tonality, although it should be noticed that physical entities are not understood from their quality of being physical but from their essenceness. Knowing that all perfections of things are caused, we can state that they are a reflex of those persisting in the cause. 

From the basic definition of God – achieved at the end of the demonstration of the thomistic ways – we can deduce some atributes and properties of the divine essence. The resemblance between the essence of the effect and the nature of the cause makes possible for us to know something about God, althoug due its transcendence, any concept will be able to correctly express the divine essence. As St. Thomas says, we don’t know God by its own form, but by the form of the creatures as an effect of the Absolute Cause. 

This doesn’t mean that our knowledge of God’s essence is merely negative, but that the essence of God is accessible to a positive human knowledge. We know something about God’s essence, but imperfectly, since known perfections must be distinguished from the way in which they are signified. In all his writings, St. Thomas notes the existence of a triple way for the natural theological knowledge of the divine essence: the way of the affirmation or the causality, the way of negation and the way of the eminence. 

The perfection of the finite must be affirmed by God as its cause by the first way; every finite mode must be eliminated in God by the way of negation; and, finally, every perfection must be placed in God infinitelly by the way of the eminence. At the end of these ways we find the Ipsum esse subsistens, i.e., the formal constitutive of God or the metaphysical essence of God. Indeed, the First Unmoved Mover, the First Uncaused Cause, the Being necessary by Itself, Maximum Entity and First ruler Intelligence, lead us to the Ipsum esse subsistens as an atribute exclusively applicable to God, ontologically original and noetically originary; the first and deepest distinctive note between God and the rest of beings. 

The path of christian philosophy passed through the elaboration of the proofs of the existence of God until that last thomistic systematisation. The radical novelty of christian philosophy – understanding God as the First – highlighted being as an act and an original ontological communication, that made possible not only concluding the principles already found in Aristotle’s thought about the priority of the act, but also discovering the proof of the creation of the entities in the existential contingency. In this hard path, a philosophical profit that – as we will see – enlightened the person and its unity (as well as the realism of its intelligence) was achieved. But, before that, let’s see other transformations that christian philosophy added to the understanding of space and time as essential characteristics of the created universe.

A first distinction that must be taken into account when determining the formal status of christian philosophy is that existing between the wise character of every philosophy and the proposal of truth that Christian Revelation offers the believer. 

Aristotle, from an early age, had already discovered that our knowledge about God comes, on one hand, through the phenomena that take place in the soul and, on the other hand, through the phenomena that take place in heights, i.e., in the beauty and movement of the stars; this way, he conceives metaphysics as the spiritual path of the search for a First Principle. The statements of the XII Book of his Metaphysics – when he states the existence of an infinite and substantial Mover – confirm the religious admiration he had since his younger days. It is not enough judging the possibility of a christian philosophy from its wise character, but we’ll have to take into account the meeting of rationality with christian Revelation in the history. 

The attitude of greek philosophy regarding the search for principles and fundamental laws geatly differs from the dialogical conscience that every christian finds regarding revelation as historical manifestation of God. Revelation means the historical manifestation of a God that is open to the dialog with the believer. 

This dialogical conscience is present in the Scriptures. “Yahvé talked to us face to face about the mountain, in the midst of the fire”. All the history of salvation is the history of a personal God that wants to communicate with mankind and stablish with it a relation based on friendship. The search for the first principles of the universe, besides manifesting rationality in its wise aspect, is far away from this personal and historical dialogue between the believer and God. 

This historical meeting with revelation will make some important differences regarding the use of reason before and after believing. Before believing – or apart from believing – the believer uses reason as the only light that allows him to understand the world. After believeing – if he does so – he will also trust reason to understand the world, since believing doesn’t mean shading reason. But now, moreover, he is in front of a number of revealed propositions – freely accepted – for which his reason acts in a different way than when facing those truths which are strictly fruit of his reflection. 

The first consequence of the meeting with Revelation is that the misteries of faith are not accepted for their intrinsic evidence but as a result of a free assent. While the greek attitude highlights the noetic aspect of intellectual adhesion, faith highlights the existential aspect in which personal adhesion is a key element. The wisdom with which greeks find the First Mover is quite different from the personal meeting with the God of history.

The second consequence implied in the meeting of man with Revelation is the conviction of the believer that, although the truths of faith overcome his natural capacity, at the same time he believes that these truths have a great intelligibility themselves. It is therefore not surprising that, after believing, the believer has a great desire to find and deepen the sense of the truths that he has believed. These two aspects of the meeting between reason and revelation are often taken into account by the Christian theologian when determining theology as the exercise of applying reason to the contents of faith. 

On one hand, he will stress the special character of the free and responsible acceptance of a number of contents of which he doesn’t have intrinsic evidence; on the other hand, he will highlight that these unreachable misteries – to reason – have an intelligibility by themselves that overcomes him. The christian theologian is someone who, after believing, tries to better understand his beliefs. Staying at this point would justify a theological discourse on the act of faith, in which we would find valuable elements about the noetics of faith, the reasons to believe, the freedom of faith as personal adhesion, the rationality of the mystery and many other contributions that would help us articulating reason and faith in both the personal life of the believer and in the rational exercise of theology. 

Even so, not only faith arises from the meeting of man and revelation – by which he becomes a believer – but also a whole new configuration of his mental universe. If the basis of a true Christian philosophy has to be found, we’ll do it in this new mental configuration. Faith produces a change in the mental cathegories in which he moved before believing – or if/when not believing – and this change implies a number of consequences that form the core of Christian philosophy, understood as the exercise of reason enlightened by faith. 

Troughout history, the work of christian theologians had major consequences, affecting the status of philosophy itself. The rational exercise applied to faith questions the very limits of the philosophical reason, specially regarding its autonomy. It will be said that philosophy is – or should be – a science autonomus from temporal realities, presented with a rational method. 

While this is true, it could also be said – without contradiction – at the same time that the certainties of faith, that the believer is trying to clarify, lead him into a mystery zone, unreachable in itself by his natural reason, but in accordance with that wise vocation of totality that we mentioned before regarding the greek thought. 

There is no true statement about reality that doesn’t affect the philosopher, wherever it comes from, even if this statement comes from Revelation or is a religious claim. Ipsum is simply dummy text of the printing and typesetting industry.