How Theology Judges the Principles of Other Sciences

IN HIS TREATMENT of the nature of sacra doctrina in the first question of the Summa theologiae, Thomas Aquinas makes a claim regarding the relationship of sacra doctrina to other, lesser forms of knowledge that is familiar to every Thomist: that sacra doctrina does not prove, but judges, the principles of other sciences. The text, which is a response to an objection, runs in full as follows:

The principles of other sciences either are evident and cannot be proved, or are proved by natural reason through some other science. But the knowledge proper to this science comes through revelation and not through natural reason. Therefore it has no concern to prove the principles of other sciences, but only to judge of them. Whatsoever is found in other sciences contrary to any truth of this science must be condemned as false: ‘Destroying counsels and every height that exalteth itself against the knowledge of God’ (2 Cor. 10:4, 5).”¹

What generally draws the attention of commentators here is the harmony between all forms of knowledge, and the superior place of sacra doctrina.² Very little attention is given to the specific claim that sacra doctrina judges the principles of other sciences. Yet on its face this is a critically important claim. Any Thomist will be, as was Aquinas himself, committed to the appropriate autonomy of any science. It is profoundly un-Thomistic to think that a theologian, just as a theologian, is an expert in philosophy, physics, psychology, or politics, for example. But if the sciences are indeed in important ways autonomous, claims regarding their relationship to a superior science must invite attention. Moreover, the expression “to judge the principles of another science” is an unusual one in Aquinas,³ which means that its meaning here may not be immediately evident from other passages.

In what follows I will first give some basic exegesis of this passage, then examine various proposed interpretations of it. I will then present my own proposal for understanding this passage, making use of a comparison Aquinas draws between sacra doctrina and metaphysics, and then giving some tentative examples of how the relationship plays itself out.

I. Exegesis of STh I, q. 1, a. 6, ad 2

To determine the meaning of the expression “to judge the principles of another science” we need to look more carefully at the text, and its context. These provide us with five points that need to be incorporated into any explanation.

A) “Sacra doctrina”

First, that which judges is sacra doctrina, the nature of which is the subject of the whole of question 1 of the Prima pars. It is both a science and a wisdom, and includes everything from the acceptance of the articles of faith, which are its principles, to their uttermost ramifications in theological conclusions.

It follows that the judgments made by sacra doctrina need not be made solely in terms of the infallibly known principles of faith. They can also be made on the basis of theological claims which are not dogmatically defined. For example, it is perfectly legitimate to appeal to a common theological opinion on original sin to make a judgment about the science of evolutionary biology.⁴ The decisiveness of the judgment will depend in part on the degree of surety with which the theological opinion is held. Such theological truths may not be known infallibly, but insofar as they are known at all they have a proper role in judging the claims of other sciences.

B) Intellectual Work

Second, the judgment we are talking about here requires real intellectual work on the part of the Christian. Sacra doctrina is a science, and science, being a movement from principles to conclusions, requires the effort of the knower to make that movement.⁵ This point is verified in what Aquinas says immediately following the text we are considering: in the response to objection 3 he distinguishes judgment by inclination from judgment by knowledge acquired through study, and says that it is the latter that is in question here. The person of simple...