Mental Reservation
### I. Concept and Historical Development
Mental reservation consists in the interior act of the mind by which one who responds inwardly alters—whether by restricting, expanding, or otherwise modifying—the meaning that his external response obviously conveys to those who hear II. Thus the response takes on a double meaning: an external one, resulting from the verbal expression and the circumstances in which it is uttered; and an internal one, resulting also from the modification introduced by the mental act of reservation. It is precisely in the double meaning of the response that the whole interest of mental reservation lies, for by virtue of its merely external meaning one may avoid indiscretion regarding one’s inner thought. Meanwhile, by virtue of its internal meaning, the response will not contradict the thought and thus, since it does not constitute a lie, will be licit.
**Historical Development of the Question.** — Already Cajetan (d. 1534) reports the opinion of many authors of his time (In 2°-2° q. 89, a. 7), an opinion which he does not consider true, according to which it would be licit to swear to an external affirmation to which one adds “a tacit condition in the mind, for example: *if I am bound*”; e.g., making an external promise, confirmed if necessary by an oath, to deliver to a blackmailer the sum unjustly demanded, while mentally adding the condition: “if I am bound.”
But not all authors were in agreement on this point. The controversies, as long as they unfolded within the ecclesiastical sphere, were always kept within the dignified limits of scholarly seriousness and charity. But when in the 17th century laymen also took part, they overflowed into an unwitting polemic, at once the fruit and occasion for the venting of personal and partisan passions. Provoked by this, the Holy Office intervened, and in March 1679 condemned the doctrine of mental reservation in two propositions (Denz.-U., 1176–77) at least as “scandalous” and “pernicious in practice.”
Following this condemnation, the advocates of mental reservation were compelled to revise their doctrine, which they then proposed within these limits. They re-evaluated the distinction, already previously proposed by some authors, between mental reservation in the strict sense and mental reservation in the broad sense. Mental reservation in the strict sense occurs when, in the modification it introduces to the external meaning of the response, no revealing traces appear either in its grammatical or syntactical structure, nor in the accompanying circumstances in which it is uttered. If, however, some such traces do appear, so that by them the response comes to assume an outwardly equivocal meaning, then one has mental reservation in the broad sense. In a rich and subtle casuistry, the nature, qualities, and limits of these equivocating traces were illustrated. Once this distinction was established and clarified, it was held that only mental reservation in the strict sense had been condemned by the Holy Office. Meanwhile, that in the broad sense, being immune from condemnation, continued to be upheld as a means of concealing one’s thought. Even this means, however, was permitted only in cases of necessity, that is, when the manifestation of thought would constitute, because of the malice or imprudence of others, a real danger of private or public harm.
In this definitive form, the doctrine of mental reservation is still accepted today by many writers on moral theology.
### II. Critical Judgment
The principles from which the advocates of mental reservation proceed and the conclusions they reach are undoubtedly sound. Namely: the intrinsic illicit nature of lying, whose essence lies entirely in the relation of contradiction between the speaker’s thought and the expression by which he manifests it; the reasonable existence of licit and valid means to conceal one’s thoughts in cases of necessity; and that therefore, in such cases, one cannot condemn—without abandoning common sense—responses that, in their obvious meaning, are equivocal or even outright false. Such responses are certainly not lies, as has been shown elsewhere (v. MENZOGNA). But that the act of mental reservation is the reason why these responses are not lies is unsustainable.
And the matter is evident with regard to mental reservation in the strict sense. For only in this way could such reservation transform a response, which without it would be a lie, into a truthful one: by altering either the thought of the speaker or his external expression; for indeed, thought and external expression in contradiction to one another are the essential constituents of a lie. Now, neither of these elements is altered by mental reservation. Not the external expression of the response; because mental reservation in the strict sense operates only in the mind, without revealing traces in the external. Nor the thought of the respondent; because it is to protect that thought in the shadows, not to change it, that mental reservation is employed. Moreover, at least mental reservation in the strict sense is condemned by the Holy Office. This is acknowledged even by its defenders, who limit themselves to upholding only mental reservation in the broad sense. But even this does not withstand criticism.
Let it first be specified that mental reservation is understood in the broad sense insofar as only part of it remains hidden in the mind, while the other part is manifested in external elements, more or less revealing. Now, with regard to that part of the reservation which remains hidden in the mind, what has just been said about mental reservation in the strict sense applies. For in both cases it operates only in the soul of the respondent, without effecting any change either in his thought or in the external expression by which he manifests II.
As for the part of the reservation that results in the external expression, granted and not conceded that it succeeds in rendering truthful a response that without it would be a lie, this would not be by virtue of mental reservation but rather by the equivocal meaning which the response now presents of itself. So much so that for the liceity of such a response, the authors do not consider the mental reservation alone sufficient, but require traces that render it, in some way, externally perceptible. And then the observation already made by Caramuel (d. 1682) in his *Theologia fundamentalis* (Frankfurt 1651, n. 1804) is all the more valid: whoever considers an expression that is equivocal in itself as a case of mental reservation considers only the name, for in such a case the expression derives another meaning, beyond the obvious one, not from the interior act of the mind, but from elements that are in the expression itself.
It has been said “granted and not conceded,” because not even an expression that is equivocal in itself preserves the response from the illicitness of a lie. But this is not the most suitable place to discuss II. We shall conclude rather with two observations: one of a practical nature, the other of a historical nature. The first is that the practical consequences deriving from the doctrine of mental reservation are most odious. For while cunning men, in the easy use of equivocal expedients, would find a convenient way to escape almost every lie, the uneducated and simple, for want of technical skill in the use of words, would not have at their disposal a licit means of defending their secrets. Yet it is self-evident that such a means must be accessible to all, and indeed especially to the uneducated, whose inferior condition exposes them more to the snares of the crafty. The second observation is that it is wrongly attributed to the Society of Jesus the paternity and patronage of mental reservation, an occasion taken to denigrate II. Apart from the name, the doctrine of mental reservation was proposed and defended from the time of Cajetan (in 1534) and the Blessed Angelo da Chivasso (d. 1495), before the foundation of the Society (1540). Subsequently, many distinguished Jesuit theologians did not adopt II. For example, Suárez (d. 1617) considered it only probable in *De religione* (in *Opera omnia*, XIII, Paris 1859, tract. 5, chaps. 9 and 10), while De Lugo (d. 1660) firmly reprobated it (*De fide*, d. 4, n. 62, Venice 1718, p. 99).