Compatibility of Reason and Faith in "Summa theologiae" of Thomas Aquinas

In researching the compatibility of reason and faith in the Summa Theologiae of Thomas Aquinas we begin from the first article of the composition in which Thomas, besides philosophy which is a rational way to the truth, shows us sacra doctrina – research gaining from the revelation of God coming into the world to testify to the truth. Summa Theologiae becomes a synthesis of two ways of knowing, according to article 8 in which St Thomas defines mutual relation of philosophy and theology. The reason furthers the belief in three ways: getting to know the truth about God the natural reason, thanks to that it is possible to refer to the authority of philosophers; refuting the charges which are in the opposite to faith and explaining difficulties (in these two situations philosophy remains autonomy – it is active in the field of revelabilia) and the reasoning in the area of truths inaccessible to reason what is helping in getting from one revealed truth to other (here we can only speak about the subservient role of philosophy in the area revelata). The purpose of the researches is to analyze the unequivocalness of philosophical terms used by St Thomas and checking the cohesion of philosophical explanations formulated both in the truths comprehensible to reason as well as in the area of truths incomprehensible to reason. This is the basic level of verification of compatibility of reason and faith remaining in the philosophy competence. Theology should check how the thesis posed in particular articles result from premises presented by St Thomas from Bible. We analyzed the application of philosophy in refuting the charges against faith where effective method turned out elaborating and redefining terms such as goodness, evil, omnipotence, omniscience, providence, freedom of will. This made possible for St Thomas to overcome the contradiction between goodness and omnipotence of God and evil in the world, between the omniscience of God and the freedom of the will and between the Providence of God and the autonomy of action of creatures. In the field of truths incomprehensible to reason it was not a success to formulate any thesis which is according to Thomas Aquinas’ philosophy. The Treatise on Trinity seems to be divergent with the Treatise on God. The problem is the knowledge of God which is His essence. In turn, the essence is common to the Three Divine Persons what makes impossible awareness of the independence because God’s essence is not composed. Also left unanswered the question of whether the three Persons can think by one intellect. Researching the compatibility of the order of nature with the order of grace turned out to be groundless because of the lack of unambiguous interpretation