Today's theological short is taken from the Summa Theologica, Part 1, Question 1, Article 1.
Whether besides Philosophy, Any Further Doctrine is Required?
Saint Thomas answers in the affirmative. Let us proceed along a line of argumentation to consider the boundaries and limits of both philosophy and theology. Objection 1 remarks that we must not go beyond what man is capable of. It is certainly true that the proper object of the human intellect is the essences of sensible beings. Human knowledge is said properly to be 'rational', in comparison we say that the knowledge of the angels and most eminently of God is 'intellectual'. For human beings, reason is a perfection, a quality that is essential to man, in fact it is what distinguishes man as a species from his wider genus of animal. As reasoning beings we proceed from what we know to what we are ignorant of. This is a process of imperfect knowledge, often uncertain, towards a firm grasp of truth. It is clear here that we must not ascribe this process to God as it would attribute imperfection and ignorance to Him. There is much stumbling and darkness along this path which the Angelic Doctor highlights later on in the article.
Human beings are utterly dependant on experience to gain knowledge as it is through the senses that we come to develop an understanding of the world around us, the particulars, but also to reach a comprehension of universals. Not being angels we are unable to grasp conclusions inherent in principles, but we must proceed step by step to arrive at an end point. We may even be wrong in our destination. For the Catholic there must be no disparaging of creation as our faculties are attuned to them to arrive at knowledge. This pertains to philosophy.
However, is it not true that philosophy does treat of God? Without a doubt. Does that mean that there is no requirement of different disciplines? Absolutely not. The justification for this negative is that theology considers God under a different light from philosophy. The material object of both sciences is God, however it is the formal object that distinguishes all disciplines. Saint Thomas remarks that both the physicist and the astronomer may reach the conclusion that the Earth is round (N.B. He wrote this in the 13th century!!!), but it is under different aspects or methods that this truth is reached. Let us apply this to philosophy and theology. Philosophy reaches a knowledge of God, such as the certainty that He exists, but this is obtained through a process of reasoning, a movement from effect to cause. Theology treats God under the formal aspect of revelation. It is founded upon the authority and certainty of God, the revealer of Himself. There are many truths that man can not apprehend by reason alone which God must show us so that we may come to know it, eg, the Incarnation, the Trinitarian nature of the Deity etc. As a corollary, supernatural mysteries can not be proven intrinsically, objections to them may be shown to be unconvincing but reason alone can not show definitively their truth value. We may know that God is, but not what He is. We 'know' the articles of revelation through Divine Faith. This surpasses the proper object of our intellects.
The Angelic Doctor remarks that revelation is for our salvation. God even reveals truths that could have been obtained through human reason alone, such as His existence. In His gracious mercy He has revealed them to us so that our reason processes which have to cope with 'an admixture of many errors' may not condemn us entirely. Our eye must be directed to God, our end but this end surpasses our reasoning capacities. Human beings make errors in thought through tiredness, inexperience, logical fallacies, the darkening of the intellect or the inclination to sin itself. It is for our own good and His glory that God willed to reveal Himself.
We conclude that theology is a necessary discipline that is formally distinct from philosophy.