Stephen Chanderbhan – “A Catholic Perspective on Comparative Philosophy of Religion”

Steve Chanderbhan is an Associate Professor of Philosophy at Canisius College (Buffalo, NY). His Ph.D. is from Saint Louis University (2012). His areas of specialization are in Medieval Philosophy (specifically, the thought of St. Thomas Aquinas), Ethics, and Catholic Social Thought. We invited him to discuss comparative philosophy of religion as part of our “Philosophers of Religion on Philosophy of Religion” series.

In Nostra aetate, a statement from the Second Vatican Council on the relation of the Catholic Church to other religions, Pope St. Paul VI declares, “The Catholic Church rejects nothing that is true and holy in these religions. She regards with sincere reverence those ways of conduct and of life, those precepts and teachings which, though differing in many aspects from the ones she holds and sets forth, nonetheless often reflect a ray of that Truth which enlightens all men.”1

I believe this follows from certain elements within the Church’s philosophical tradition, which I lay out below. Given this, comparative philosophy of religion should be commended in Catholic contexts as a way that the true and holy in other religions may be discovered and studied.

First, reflections of “a ray of Truth which enlightens all men” are a reference to the notion of illumination, found most notably in the Neoplatonic thought of St. Augustine. Illumination picks up on an interpretation of Plato’s Allegory of the Cave. The fire inside the cave is necessary for the shadows on the cave wall to be seen, this represents that which makes things sensible in reality. Similarly, the Sun outside the cave is necessary for the things outside the cave to be seen; this represents that which makes things – namely, Forms – able to be known by the intellect. This is the light of illumination, which Augustine calls a kind of “incorporeal” light.2

For Augustine, God is the cause of this illumination. In De libero arbitrio, he writes:

[A] strong, vigorous, mental gaze, when it sees with certainty many unchangeable truths, turns [above] to the Truth itself in which all things are shown … If I showed there was something above our minds, you admitted you would confess it to be God, provided there was nothing else higher. I accepted your admission, and said it was enough that I should show this. For if there is anything more excellent, it is this which is God, but, if there is nothing more excellent, then Truth itself is God.3

God’s illumination refers to a necessary condition of any and every instance of knowledge for anyone. Little wonder that this “ray of Truth,” which is of God, shines on all. As knowledge of causes can be inferred from their effects, it follows that God, to some degree, may come to be known as the ultimate cause of that which one truly knows in any instance of knowledge.

But what is knowledge? A classic formulation is expressed in St. Thomas Aquinas’s De veritate: “The first reference of being to the intellect … consists in its agreement with the intellect. This agreement is called “the conformity of thing and intellect” (adaequatio rei et intellectus). … Knowledge of a thing is a consequence of this conformity.”4 A couple things follow that help to vindicate comparative philosophy of religion.

First, what is adequate to the intellect is being, not facts or propositions.5 Granted, propositions are a primary way in which knowledge is communicated; and right belief (i.e., orthodoxy) is necessary in framing a religion’s belief system. At the same time, no religion’s insight to Truth is exhausted just by what propositions are true in it; nor can one say that the “ray of Truth” has not touched a religion if it contains any (or even many) false propositional beliefs.

Second, given this characterization of knowledge, the essence of God is something to which no human intellect, nor any collection thereof, can ever be adequate in their natural state. The fundamental being, or essence, of any species (i.e., kind) of natural being is expressed in terms of the definition of that species. This definition has two parts: genus and difference. For example, a human is essentially an animal (genus) who is rational (difference). When humans’ metaphysical nature, or essence, is adequate to the intellect, whatever is signified by the definition “rational animal” is fully present in the intellect. So too for any case of knowledge of species.

God, however, transcends all species and genera of natural being; hence, God has no proper genus-difference definition. St. Anselm, for example, characterizes God as “that than which no greater can be conceived;” while that characterization points solely to God, “that than which” is not a proper genus.6 Since God’s essence cannot be expressed in a definition, full adequation with the intellect as it operates in this life is impossible.

Full knowledge of God’s essence is only attained when we see God as He is. God exists in eternity and, thus, transcends time and space. While we are limited by those things, we cannot see God as He is – even if our knowledge is supplemented by insights of Divine revelation held by religious faith. Full knowledge only occurs in the Beatific Vision, in the afterlife. This life, on the other hand, is a “journey of the mind into God,” quoting St. Bonaventure’s famed work.

The implication is that no religion’s totality of theology, sacred texts, etc., can capture the essence of God fully. As such, no religious tradition, even if augmented with claims of Divine revelation, could rightly consider itself a closed, self-sufficient system. That would belie God’s transcendence and the limitations of human knowledge. Hence, other religions can be treated, not as alien, but as holders of some Truth and Goodness (i.e., Holiness), touched by God’s “ray of Truth.” Accordingly, they are worth studying on this journey. This does not mean there cannot be definitive dogmatic boundaries on what ultimately is to be believed within a religion; however, those boundaries need not close one in on all sides.

I leave unanswered the questions of what Catholics may gain from studying other religions and whether comparative studies would enrich and deepen one’s faith or endanger it by introducing near occasions of confusion. All I claim is that Nostra aetate’s statement is grounded in a philosophical tradition privileged by the Church and that this ultimately commends comparative philosophy of religion.


1. Pope St. Paul VI, Nostra aetate: Declaration on the relation of the Church to non-Christian religions (Vatican City: Vatican Council II, 1965), §2.

2. St. Augustine of Hippo, De trinitate, translated by Arthur West Haddan, in Nicene and Post-Nicene Fathers, First Series, Vol. 3, ed. Philip Schaff, (Buffalo, NY: Christian Literature Publishing Co., 1887), XII.xv, website,

3. St. Augustine of Hippo, De libero arbitrio, translated by Dom Mark Pontifex, (London: Longmans, Green and Co., 1955), II.xv.39, website,

4. St. Thomas Aquinas, Quaestiones disputatae de veritate (Questions 1-9), translated by Robert W. Mulligan, S.J., (Chicago: Henry Regnery Company, 1952), q. 1, resp., website,

5. Working within a broadly Aristotelian-Thomistic framework, Alasdair MacIntyre appreciates this point as follows: “The relationship of correspondence or lack of correspondence which holds between the mind and objects is given expression in judgments, but it is not judgments themselves which correspond to objects or indeed to anything else. … What is and was not harmless, but highly misleading, was to conceive of a realm of facts independent of judgment or of any other form of linguistic expression, so that judgments or statements or sentences could be paired off with facts, truth or falsity being the alleged relationships between such paired items. … It is a large error to read [this kind of correspondence theory] into older formulations concerning truth, such as ‘adaequatio mentis ad rem’ …” (Alasdair MacIntyre, Whose Justice? Which Rationality? (Notre Dame, IN: University of Notre Dame Press, 1988), p. 357-358.)

6. St. Anselm of Canterbury, Proslogion, in The Devotions of St. Anselm: Archbishop of Canterbury, translated by Clement C. J. Webb, (London: Methuen & Co., 1903), Ch. 2.

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