The Thomist Critique of the Principle of Sufficient Reason

A Guest Article

I was very glad when my friend Vini reached out to my about my recent article titled ‘The Principle of Sufficient Reason: A Thomist Critique?’ As I indicated in my introduction, the Principle of Sufficient Reason was not universally regarded in a positive light among scholastic authors. Vini wished to provide a supplement to my case as written from a different perspective.

While I remain unconvinced of the case as presented (as admirable of a case as he presented), I do believe that this is a worthwhile case to present to you, the reader.

-Christian B. Wagner

Introduction

My great friend Christian B. Wagner has posted a very interesting article about the Principle of Sufficient Reason (PSR). He did something really nice in collecting the testimony of a considerable number of neo-Thomists in favour of what they call “principle of sufficient reason”. Sanseverino, Zigliara, Hugon, Gredt, Mancini, Kleutgen, Garrigou-Lagrange and others unquestionably employed the principle, and they did not regard themselves as having thereby abandoned St. Thomas for Leibniz. On the contrary, they commonly distinguished between a false or exaggerated Leibnizian use of the principle and what they took to be its sound Scholastic substance.

Such historical points are absolutely true and correct, but I believe some surrounding questions deserve some clarification. For example, the article claims that “it is important … to consider carefully how the Thomists actually interacted with the PSR.” But the list of authors analysed are nineteenth and twentieth century post-Leibnizian neo-Thomists — which still leaves us the room to see how the more traditional commentators of St. Thomas would have interacted with Leibniz or did in fact interact with him.

Also, the neo-Thomist claim is not merely the harmless assertion that things are intelligible, or that one may speak broadly of a ratio where no proper cause is involved. The claim is considerably stronger. Cause is subordinated to the PSR, which is presented as analytic, per se notum, and ultimately reducible to non-contradiction. And the principle of causality, according to them, is to be derived from the PSR, as says Garrigou:

“From the general principle of sufficient reason derive the principles of efficient causality and finality.” (Garrigou-Lagrange, La Synthèse Thomiste)

Cornelio Fabro adduced several criticisms to such notion of PSR, which, in my understanding, are absolutely correct. Fabro expressly names Descoqs, Maritain and Garrigou-Lagrange as committing such mistakes. His alternative was a return to the properly Thomistic notions of participation and actus essendi.

I. What Is Meant by “Principle of Sufficient Reason”?

Wagner deliberately abstracts from Leibniz’s particular system and asks whether the bare maxim nihil sine ratione sufficiente may be vindicated independently of its later rationalistic accretions — and we will see how we can truly formulate a certain “Thomistic PSR” afterwards.

This abstraction, of course, depends a lot on what sufficient reason actually means.

Buonpensiere’s hierarchy, adopted in the article, may be represented as follows: sufficient reason explains, a principle adds real distinction, a cause adds real dependence. There is something initially plausible in this. Ratio is plainly broader than causa. One may speak of the reason for a definition, a property, a conclusion, a divine volition, or an intelligible distinction where no efficient cause is in question.

Fabro, however, insists upon a distinction which is easily blurred. In his article “Causa”, he characterizes cause by real dependence, whereas ratio belongs to the order of explanation. From the greater logical extension of ratio it does not follow that causality is metaphysically founded upon a universal principle of reason. The move from “ratio includes causa” to “the principle of sufficient reason grounds causality” is not a logical truism. It is a metaphysical thesis, and it must itself be established.

Thus the ambiguity must be faced at once. Does sufficient reason signify merely an intelligible account, or does it signify a real ontological ground? If the former, it does not yet give us causality. If the latter, causal dependence has already entered under another name.

II. Leibniz’s Principle and the Neo-Thomist Reconstruction

Leibniz’s own formulation is more determinate than the one later given by Gredt and Hugon.

In Monadology §§31–38, contradiction and sufficient reason are introduced as distinct first principles of reasoning: “Our reasonings are founded upon two great principles, that of contradiction, by virtue of which we judge that to be false which involves a contradiction, and that of sufficient reason, by virtue of which we consider that there can be found no true or existent fact, or any true assertion, unless there be a sufficient reason why it is thus and not otherwise.”

Gredt’s ratio sufficiens is that whereby something is what it is (Elementa, vol. II, n. 749) — which is already a very bad definition to ground the principle of causality. Hugon similarly extends sufficient reason to quiddity, existence and intelligibility (Cursus, Metaphysica, tract. IV, q. I, art. IV). The definition of what they understand in the principle has therefore shifted. While Leibniz is mainly concerned with why proposition p rather than not-p, the neo-Thomists ask by what is A determinately A. Analytic philosophers also tend to prefer a logical Leibnizian PSR rather than an ontological PSR.

So if neo-Thomists made the concession of language to have a better dialogue with other Philosophies, why does the principle carry a whole different meaning?

III. From Sufficient Reason to Non-Contradiction

Now, no Thomist denies the necessity of the causal principle. Nor does he deny its immediacy. In “Causa” Fabro explicitly treats it as per se notum and distinguishes the modes of perseity.

The dispute concerns the proper subject of the proposition.

St. Thomas gives the decisive true Thomistic formulation in ST I, q. 44, a. 1, ad 1:

“From the fact that something is a being by participation, it follows that it is caused by another.”

For him, therefore, the principle of causality is taken from participation, not from a generic search for sufficient reason. This is where Fabro’s criticism becomes constructive. The necessity of causality is not secured by reducing being to a thin logical concept and then extracting from it a principle of reason. It appears once finite being is grasped in its proper ontological constitution.

IV. The Ambiguity in the Neo-Thomist Proof

The notion of sufficient reason now divides.

If it means simply “that whereby something is determinately actual”, then the principle is incontrovertible. Whatever is actually something must possess that whereby it is actually such a thing.

But nothing extrinsic follows from this. “A is determinately actual” does not by itself entail “there exists an explanatory ground why A is rather than is not”.

If, on the other hand, sufficient reason means an ontological ground which accounts for why this actuality obtains, then the principle is much stronger; yet that stronger sense is no longer contained analytically in non-contradiction and must be further justified.

The Thomistic doctrine of participation avoids the problem because it does not infer dependence from a generic demand for explanation. It discovers dependence in the very mode according to which actuality is possessed.

V. The More Serious Difficulty: Esse Is Not One Determination Among Others

Hugon’s division of sufficient reason into reason of essence, existence and intelligibility appears at first admirably comprehensive.

From an authentically Thomistic perspective, however, the arrangement is already suspect. For St. Thomas, esse is not simply another formal determination ranged alongside essence. It is the act through which essence itself is made actual.

Fabro’s central hermeneutical thesis is precisely that St. Thomas passes beyond the Aristotelian primacy of form by reaching the intensive act of esse, the actus omnium actuum.

Composition, participation and causality consequently converge upon this act. Fabro repeatedly insists that composition, causality and predication receive their ultimate metaphysical unity from esse.

The Neo-Scholastic schema tends to proceed horizontally: essence, existence, and intelligibility. All fall under the common rubric of sufficient determination.

The Thomistic resolution is actually vertical: formal act, actus essendi and esse participatum.

The correct metaphysical question is therefore what does it mean for a finite essence to have esse?

Once that question is posed properly, participation is already before us. And the words of St. Thomas already cited support the conclusion that this is how he truly inferred causality.

If that question is posed properly, participation is already before us. And the words of St. Thomas already cited support the conclusion that this is how he truly inferred causality.

VI. The Classical Thomistic Resolution: Thomas, Capreolus, Cajetan

The traditional commentators of St. Thomas — and this point Fabro misses — also deduce the principle of causality from participation. Capreolus says:

“Everything that is a being by participation is derived from the being by essence, which is God.” [20].

And he argues that participated agents cannot produce esse simpliciter. Finite causes act upon already constituted subjects; God alone, as ens per essentiam, communicates being absolutely.

Cajetan reads the same article within precisely this participation-causality structure:

“Whatever is found in something by participation is caused by that in which it exists by essence.” (In Ia, q. 44, a. 1)

And defining the participatory side:

“A thing, however, is constituted by participation through the contraction of the amplitude of some formal ratio, in whatever manner this occurs.” (ibid.)

What is noteworthy is what these authors do not require. They do not interpose the deduction: “everything has a sufficient reason, therefore the creature’s sufficient reason is extrinsic, therefore cause.”

Their movement is more direct: “esse participatum, therefore dependentia causalis.”

A great example of an analysis on how finite participated being implies the necessity of causal dependence can be seen in Appendix A of another article I wrote regarding the principle “whatever is moved, is moved by another”. Even though it is just a particular case (i.e., motion), it still can serve as reference.

VII. Ratio Is Broader Than Causa—But Not Therefore Deeper

The neo-Thomist hierarchy of “causa, principium, ratio” may be conceded as one of logical extension, but not as one of metaphysical resolution.

To demonstrate the existence of God causa must signify real dependence, ratio need not. That distinction is enough to dissolve the inference.

A concept can be more universal precisely because it contains less determination. Thus the proposition “every cause may furnish a ratio” does not have to entail “causal dependence is metaphysically derived from universal ratio.” We can concede the former, but not necessarily the latter — and St. Thomas never makes such an inference. The latter, in fact, confuses logical inclusion with ontological foundation.

And it is precisely this conversion of causa into ratio which Fabro identifies as characteristic of rationalism.

VIII. Causality Secundum Fieri and Causality Secundum Esse

Wagner’s sharpest claim is that causality concerns becoming, whereas PSR concerns being. Hugon speaks of what “comes to be”; Gredt describes cause as an extrinsic ratio fiendi.

Fabro certainly acknowledges creaturely causality secundum fieri. Predicamental causes produce determinations and changes within an already constituted world.

But this is not the whole of causality. Above predicamental causality stands transcendental causality, whose proper terminus is the creature’s esse. Fabro expressly distinguishes the causal participation involved in creation from the causal order of finite becoming. [28]

Hence his distinction causalitas infinita secundum esse proper to God, and causalitas finita secundum fiere, proper to created agents.

IX. Why Participation Is the Final Formula

Fabro examines a number of traditional formulations of the causal principle: omne quod movetur ab alio movetur; whatever begins requires a cause; potency requires actuality; the contingent requires a cause; the composite requires a composing cause; etc.

Each is valid, but each is limited. Motion is too narrow; beginning excludes the possibility of an eternal creation; contingency does not embrace every being necessary ab alio; composition reaches deeper, especially when it concerns essence and esse.

Participation alone expresses the whole transcendental dependence. Participation includes at once similarity, distinction, and dependence.

The creature really possesses actuality; it is therefore not nothing. But it possesses actuality participative: it is not identical with the act it possesses. Participation expresses the structure; causality the dependence of that same structure upon its source.

No more universal PSR is required over both.

X. The Proper Thomistic Resolution

Fabro’s positive doctrine may now be stated in its own terms.

Metaphysical resolutio does not proceed by passing from causality to sufficient reason and from sufficient reason to contradiction. It proceeds within the real.

From an accidental act, one resolves to substantial form; from form, more profoundly, to actus essendi. All formal acts are ultimately actual through esse, the intensive act which actuates them. Finite ens consequently appears not merely as “something which is,” but as id quod habet esse. The creature has esse; it is not ipsum esse. And from this we can deduce that omne quod movetur ab alio movetur; whatever begins requires a cause; potency requires actuality; the contingent requires a cause; the composite requires a composing cause; etc

God, as Esse per essentiam, is therefore the actuating cause of finite esse per participationem.

This is not a merely alternative route to the same conclusion. It is another conception of metaphysics.

XI. Conclusion

The modern Thomists cited by Wagner need not be dismissed, nor should the expression ratio sufficiens be treated as philosophically unclean. Much of what they intend by it is unobjectionable.

The distinctions, however, must be preserved.

If PSR means “whatever is determinately actual has that whereby it is determinately actual”, it is true, but it is not quite what we need for the proof of God’s existence.

If it means “every contingent actuality must possess a determining explanation why it is this rather than otherwise”, I deny that this follows analytically from non-contradiction.

If ratio sufficiens is employed broadly for formal, logical, final and causal reasons, I agreed quoad extensionem; and deny quoad resolutionem.

And if PSR is proposed as the metaphysical principle from which real causality itself is to be derived, I also deny.