Mortimer Adler’s Truth in Religion treats a difficult topic. Our scientific worldview has taught us that material and/or experimental proof is the only valid test for truth, and our pluralism tells us that we must be tolerant of other’s views. Since religious truth is improvable by scientific methods, and since the plurality of religions makes it difficult to hold that one religion might possesses the fullness of truth, how can we speak of truth in religion?
Religious Pluralism
First, Adler discusses plurality. He distinguishes between matters of taste and matters of truth. Matters of taste would include food, clothing, entertainment, political views, etc.; insofar as none of these contains any truth, they are all subject to matters of taste and therefore a plurality of these things is both good and necessary. Matters of truth would include all scientific, historical, philosophical, and religious truth, and they exclude the possibility of plurality.
To understand this distinction, we need to understand that Adler is speaking of logical truth. In On Interpretation, Aristotle distinguishes between contradictory statements and contrary statements. The statement “God exists” is contradictory to the statement “God does not exist,” and therefore one statement is true and the other is false, for God either exists or does not; there is no middle ground.
Contrary statements have more leeway. “Christianity is true” and “Islam is true” are contrary; both statements cannot be true because Christianity and Islam contain doctrines that are incompatible with one another. Yet, both Christianity and Islam may be false and another religion — Judaism, for example — may be true. So whereas contradictory statements necessitate that only one statement is true and the other is false, contrary statements allows that one statement may be true, but also that both statements may be false. Thus, when Adler speaks of matters of truth, he means matters of logical truth.
Insofar as religions contain matters of truth (doctrines) and not just matters of taste (forms of prayer), religions are subject to the logic of truth. Since plurality is possible only in matters of taste, we cannot accept religious pluralism so long as religions hold to matters of truth. Just as we exclude pluralism from the domains of science, history, and philosophy, we must exclude pluralism from the domain of religion. We cannot accept with intellectual honesty the possibility of religious pluralism.
A side note: Not all religions contain explicit doctrinal or creedal statements; some religions contain only ethical codes. Adler contends, however, that all ethical codes assume a doctrinal framework. Take, for example, the Golden Rule. We find it in creedal religions as well as non-creedal religions. Even without an explicit creedal statement, this simple and universal ethical code implies a creedal framework: (a) that human beings are distinct from animals, (b) that human beings are the same, (c) that there is a universal good for all human beings, and (d) that we can know what this universal good. If ethical statements contain implicit doctrinal assumptions, even religions without doctrinal statements are subject to the laws of logical truth and, therefore, are either true or false.
Religious Truth
Some will say religious truth is impossible because we cannot prove religious creeds by scientific experiment. Adler points out that we prove neither historical nor philosophical truth by scientific experiment; the different sciences have different means at arriving at truth. If this is the case with science, history, and philosophy, it is also the case with religion.
Yet, religion is different insofar as religious claims are beyond what human can know through reason alone. Almost all religions claim their doctrines were revealed by superhuman means. In the Catholic faith, we call this Divine Revelation. Though a philosopher can prove philosophically that we can trust our senses or that God exists, no creedal religion can prove its creedal statements. But just because a religion cannot prove its creedal statements does not mean religions are not subject to the laws of logical truth. “Jesus Christ is God” and “Jesus Christ is not God” are contradictory statements. Though we cannot prove which statement is true and which is false, that does not mean that one is true and the other is false, for Jesus Christ cannot be both God and not-God.
Still, there is a matter of practical difficulty: if we cannot prove which creedal statement is true, what are we to do with the man claims to religious truth? How is one who is devoted to the truth to navigate through the world’s many religions? Don’t we have little hope in knowing truth if we have no help deciding which religion is true.
To answer this difficult problem, Adler appeals to a medieval debate. Averroes (d. 1198) was an Islamic philosopher who said that there are two distinct kinds of truths, the truths of religion and the truths of science and philosophy; he said this in an attempt to reconcile the contradictions between his Aristotelianism and his Islamic religion, and by saying it caused a firestorm within medieval Islamic communities. In the 13th century, this debate carried from the Middle East to Christian Europe, and St. Thomas Aquinas found himself in the middle of it. St. Thomas’s answer was simple: just as God is one, truth is one; just as God is a unity, truth is a unity; therefore, we cannot separate scientific truth from philosophical truth from religious truth. If a scientific, philosophical, or religious claim contracts a claim made by the other two fields, we have made an error in thought, the contradiction is in appearance only.
Thus, the principle of the unity of truth is the way to begin answering the question, Which religion is true? If creedal statements (either explicit or implicit) contradict what we know with certainty from science, history, or philosophy, we know those religious statements are false.
Thus, any religion that make creedal statements must be willing to subject these statements to the unity of truth. The creedal statements cannot contract known fact. The upshot of this, which Adler only hints at, is that if any religion can pass the test of the unity of truth, that religion will bring coherence to what we know through science, history, and philosophy. The religion will do for the intellect what it does for the soul-bring healing and wholeness.
Conclusion
Adler’s point in Truth in Religion is not to declare which religion is true. His point is to establish the philosophical foundations needed in order to begin answering the question. However, Adler is willing to take one step in this direction. Insofar as they all reject the philosophical truth that one God exists, and insofar as they reject the unity of truth (in other words, they maintain an implicit Averroism), Adler claims all Far Eastern religions are false. He is left with the three great Western monotheistic religions — Judaism, Christianity, and Islam — and he leaves it at that.
Truth in Religion is not an easy book. The subject matter is both difficult as well as personal. To think logically and philosophically about any topic is hard, but when the topic is as personal as religion, the book takes on special problems. Readers who have Averroistic tendencies — readers who want to keep religious truths separate from scientific, historical, and philosophical truths — will have tremendous problems with Adler’s book. Those, however, who believe in the Thomistic principle of the unity of truth will find that Adler’s book is a profound reflection on the philosophical foundations of religious truth as well as an excellent book concerning the philosophical foundations of apologetics.
Highly recommended.