Shahin Aawani * Among the famous thinkers who lived in the seventeenth century after Descartes (1596-1650), one is Blaise Pascal (1623-1662), and the other is Nicolas Malebranche (1638-1715). All the three are reckoned among French rationalist thinkers. There are some similarities between Descartes and Pascal. They are both philosophers, mathematicians and of Catholic denomination, but they represent two different lines of thought. Pascal starts, strictly speaking, from experience. Pascal does not simply accept the authority of reason, and he says that if reason were the ultimate authority, rationality would certainly be sufficient in itself and there would be no need for revelation, but rationality has not yet found a universally accepted truth. Pascal's logic is neither Aristotelian nor Cartesian, rather his logic is the "logic of the heart" in which the primordial human nature, that is, inner intuition, must be distinguished from reason. In contrast to Descartes' famous dictum "Cogito ergo sum" (I think, therefore I am), Pascal stipulates "Credo ergo sum? " (I believe, therefor I exist? ), where "thought" is supplanted by "belief". Of course, in Pascal's philosophical system, "thought is the basis of human glory and grandeur"; and the foundation of ethics in his philosophy consists in thinking and acting in the right way, therefore he seeks all the human virtues in human thought. He maintains that truth cannot be found and truly believed in through reason. Descartes with his methodic doubt and his clear and distinct ideas reached only "conceptual certainty" but he never delved into the reality of faith. Philosophers have generally identified Pascal as a rationalist, but this article proves that he is a "Fideist", and on this basis, the author examines the subject of religion and faith in the heart from Pascal's point of view. In addition, the present article examines the logic and method by which Pascal arrives at "faith" and "religion. " Pascal distinguishes between faith, levels of faith, and wisdom. He believes that faith is a grace bestowed by God on a believer. At this stage, faith is for the general public and beginners, but when faith gives way to mysticism, it is at this stage that the believer becomes a mystic and achieves an understanding of the truth. Such an argument is presented in Pascal as the difference between philosophy and wisdom, where he says: "The greatness of wisdom, which is only valid when it comes from God, is invisible to carnal and spiritual people. " He goes on to write: “ The great geniuses have their triumph and their fame, and they have absolutely no need of carnal greetings to which they have no relation, for this neither adds nor deprives their own greatness” . They are seen by God and the angels, not the bodies or the inquisitive followers. God is enough for them (Pascal, 1997: 308/793). One of the key phrases of Pascal's thought is: "The heart has its reasons, which intellect does not know"; the truth of God is such that it is both apprehended by intellect and intuited by heart, because “ it is heart that knows the principles” . To show Pascal’ s opposition to reason, the word “ qalb” proves to be more logical and precise than “ dil” and feeling. According to Descartes, “ heart” is a bodily organ that all living creatures have in common, but reason, as the faculty of reasoning and arguing, is peculiar to “ human beings” , equally distributed among them. Pascal, in contrast, explicitly asserts that this is the heart that apprehends “ mysteries of faith” . God is visible by heart, not by reason. The heart naturally loves “ transcendent beings” . Pascal maintains that man does not need to be grandiose, since he is but a reed, that is the weakest creature in nature; but he is a thinking reed. The entire universe need not arm itself to crush him. A vapor, a drop of water suffices to kill him. But, if the universe were to crush him, man would still be more noble than that which killed him, because he is aware of his mortality. The universe knows nothing of this. “ All our dignity consists, then, in thought. By it we must elevate ourselves, and not by space and time which we cannot fill. ” so we should endeavor to “ think well” ; this is the principle of morality. Unlike the rationalists, Pascal holds that God is not conceivable through rational procedures. Two centuries later, the same central thesis was developed and articulated by Soren Kierkegaard (1813-1855), the existentialist theologian, in a more precise and modern formulation. Both consider the quest for evidences to prove the existence of God as a kind of disrespect for religion, because it inevitably consequents on a preceding doubt and lack of conviction. Both accept revelation as the basis of their faith. Pascal, however, trusted on God’ s graciousness, contrasted the religious worldview with the scientific and philosophical rationalizations. Pascal claims that he has found the ultimate foundation of the certainty on which everything depends. This foundation is the living God, i. e. the Bible, which was revealed in Jesus and is historically present in him. Is such a claim true? In that case, can he be called a "philosopher of religion"? Meanwhile, Pascal's unfinished and most important work, entitled Pensé es (Thoughts), is written about the legitimacy of the religion of Christ defending it against its adversaries. He is a devout philosopher, and a staunch supporter of the Catholic religion, yet he is a moderate believer. His famous work, Fragments: Penseé s, is on the legitimacy of the religion of Christ and its defense. According to Pascal, attaining God is the work of the heart, not the intellect, because the intellect either leads man to heresy or makes him an atheist. The issue is complicated by the fact that “ heart” — in German: “ Herz” — has been rendered into Persian by the word “ dil” , while its true equivalent is “ qalb” . As mentioned in the article, Pascal attributes the center of intuition and vision of God to the heart as “ qalb” , rather than “ dil” — which is concomitant of arbitrariness; thus, if one considers Pascalian notion of heart as “ dil” , the knowledge of God would be understood as subjective, instead of as a knowledge by heart and faith. In the present article, the author has tried to first enumerate Pascal's scientific innovations in the field of natural sciences, hydrostatics, etc. She then goes on to describe Pascal's important intellectual points, including his inclination toward religious discourse-as well as Pascal betting on the existence of God, Pascal triangle, and Pascal's theorem. Moreover, another section of the article is particularly concerned with the relation of faith to the issue of predestination and free will, and to the law. Here, the question arises as to whether or not predestination and free will are considered to be distinct from each other in Pascal’ s fideism, as it is the case with Christian theology. How is this issue addressed by his “ logic of the heart” ?