DEISM. — Etymologically, deism (from *Deus*) is identical with theism (from *Theos*); but its philosophical and historical meaning is different. The philosophical meaning commonly accepted today is that already defined by Kant: the deist “admits that we... can know through mere reason the existence of an original Being, but... only as a Being who possesses all reality, though we cannot determine it more precisely”; the theist “affirms that reason is capable of further determining the object according to the analogy of nature, that is, as a Being who contains within Himself the first principle of all other things through intellect and freedom. The former represents in such a Being merely a Cause of the world (whether through the necessity of His own nature or through freedom remains undecided), the latter a Creator of the world”; and a little further on: “the deist believes in a God, but the theist in a living God (summam intelligentiam)” (I. Kant, *Kritik der reinen Vernunft*, 1st ed., Riga 1781, pp. 631–33; cf. Italian trans., 2nd ed., Bari 1925, pp. 493–94).
Historically, deism does not have such a narrow and fixed meaning. In general, it denotes that philosophical-religious movement of the 17th–18th centuries—preliminary to, intertwined with, or merging into the Enlightenment—which aimed to eliminate every supernatural element from religion and to establish a purely natural religion. In practice, it took various forms. At the beginning of the 18th century, Samuel Clarke (1675–1729), an opponent of deism, in *A Demonstration of the Being and Attributes of God* (London 1705) distinguished four classes of deists: 1) Those who admit God but deny all providence: God, as an intelligent cause, drew the world from chaos and then left it entirely to itself. 2) Those who admit providence but only for physical events: God takes no interest in moral good and evil, which arise solely from positive laws; there is no future life for man. 3) Those who admit providence even for moral life: the moral law is from God, but there is no immortality, and hence no sanction in a future life. 4) Those who accept all natural truths about God, admit a future life, but reject every religious authority and revelation.
The term *deist* appears in the 16th century. The Calvinist pastor M. Viret, in the dedicatory epistle to Part 2 of *L’Instruction chrétienne* (1564), speaks of it as “a quite new word, which they (the deists) wish to oppose to atheism.” Of their ideas he says: “While acknowledging God, they do not admit Jesus Christ. The teaching of the Apostles and Evangelists is to them pure fable and fantasy.” The word’s use spread in the 17th century. Until the 18th, and even into the early 19th century, the term *theism* (of English origin, popularized especially by Ralph Cudworth, [1617–88]) was sometimes used in the same sense.
Deism had its systematic advocates first in England, where, however—at least until D. Hume and E. Gibbon—it remained, both in scientific and literary value, a movement of secondary importance. Among its principal representatives, especially noteworthy are J. Toland (1670–1722) and M. Tindal (1656–1733). In *Christianity not Mysterious* (London 1696), Toland intends to demonstrate, as the subtitle states, “that there is nothing in the Gospel contrary to Reason, nor above it, and that no Christian doctrine can properly be called a mystery.” Revelation is admitted, but “revelation serves only to inform us, while the demonstration of its object is what persuades us.” Tindal, in his work (often called *The Bible of Deism*), *Christianity as Old as the Creation; or, the Gospel a Republication of the Religion of Nature* (London 1730), seeks to show that natural religion was absolutely perfect from the beginning; that revelation could add nothing to it; and that Christ restored natural religion or the law of nature. Other notable English deists were A. Collins (1676–1729); Th. Chubb (1679–1747); Th. Morgan (d. 1743); and Lord H. Bolingbroke (H. St. John, 1678–1751), friend of Voltaire, whom he met during his exile in France and later hosted in England for three years.
English deism partly derived from France. In France it returned more developed and was spread especially through the efforts of Voltaire, Rousseau, and the Encyclopedists. A revival occurred in the 19th century with Cousin and the spiritualists.
In Germany, deist ideas arrived both directly from England and via France, merging and developing within the broader Enlightenment movement. Among its proponents were H. Samuel Reimarus (1694–1768), known especially for *Apologie oder Schutzschrift für die vernünftigen Verehrer Gottes*, published posthumously (1774–77) in part by Lessing as fragments of an anonymous work found in the Wolfenbüttel library (in Brunswick); M. Mendelssohn (1729–86), the most notable representative of “popular philosophy,” often cited by Kant; and especially G. E. Lessing (1729–81). In his most mature work, *Erziehung des Menschengeschlechts* (Berlin 1780), which exerted influence beyond his time, he treats the Old and New Testaments as historical products—not arbitrary, but grounded in the intrinsic law of humanity’s development. They are products of its childhood and youth; it is for maturity to discover in their dogmas the rational truths inherently adumbrated within them. Kant, as regards the concept of God, is a theist in his own way (the existence of God is not demonstrable speculatively, but only from the moral law of man, as a mere practical postulate); yet in his concept of religion he is to be counted among the deists.
Deism as a historical phenomenon is chiefly explained by the weariness and skepticism produced by the religious conflicts between Catholics and Protestants, and even more among Protestants themselves. Evidence of this is seen in the fact that, while deism spread in England, France, and Germany, it met with only weak resonance in Italy (which had nonetheless provided English deists with suggestions and ideas) and in Spain.
Among the various ideas carried by the deist current, the fundamental one is that of natural religion, affirmed by deism as the only true and legitimate religion. For this claim to be firmly grounded, one would have to demonstrate either the impossibility of revelation, or its factual non-existence, or finally that, even if revelation is admitted to exist, it lacks the requisite qualities to demand our assent.
The impossibility of revelation could be maintained only on the presupposition of an impersonal God, who acts not as an intelligent and, in His external operations, free cause, but as a blind and necessary natural force—that is, on the presupposition of a God conceived pantheistically. The fate of this hypothesis is tied to that of pantheism.
To demonstrate that revelation has in fact never occurred, one must dismantle its factual proofs—that is, those derived from supernatural facts. This could be done by denying either the historical reality of such facts or their supernatural character. This was the path taken by Reimarus, whose work was published in fragments by Lessing. On the value of such attempts, see especially: GESÙ CRISTO; RIVELAZIONE.
Setting aside this question, one may instead attempt to demonstrate that, even if supernatural facts were to exist, from them certainty regarding the propositions of faith cannot be deduced. The argument now enters the philosophical sphere; and it has been formulated in the most technically precise manner by Lessing: “contingent historical truths can never serve as proof of necessary truths of reason.” This principle is closely connected with the general epistemological problem: whether universal and necessary knowledge can be derived from particular and contingent knowledge. Kant, as is well known, started precisely from the negative answer in which empiricists and rationalists concurred, to formulate the theory of the synthetic a priori judgment. In our case, one may, in part, abstract from this problem, provided that the objective validity of the principle of causality is admitted. For here the issue is not to prove from historical facts the revealed truths (which are necessary), but merely that God has spoken; thus from contingent facts, a contingent fact (revelation is, as a fact, contingent, since it is free on God’s part). And the necessary truths of faith derive, properly speaking, not from the contingency of the fact of revelation, but from the necessary veracity of the author of this fact.
To reach the ultimate roots of the problem, one would still have to examine whether from a historical fact one can ascend to God as a sufficient reason. This problem, however, is merely one aspect of the general question: whether from the contingent it is possible to ascend to God, the necessary Being; on this question see God.
As for the technical meaning that the term “agnosticism” has in philosophy, it appears as an inconsistent compromise between agnosticism and theism. It seeks to affirm the knowability of God’s existence while denying the knowability—even analogical—of His nature. But the unknowability of God’s nature also entails that of His existence. For when it is unknown of God whether He is transcendent or immanent to the world, an intelligent and free cause or a blind natural force, in reality His existence is unknown: since an immanent God (in the pantheistic sense) is God only in name, and a blind force is not even that. Agnosticism therefore possesses only the apparent consistency of confused concepts.
Scarcely is it thought through to the end—that is, truly thought through—does it dissolve: into pure agnosticism, if one explicates what agnosticism implicitly contains in its negative aspect (unknowability of the divine nature); into theism or pantheism and atheism, if one specifies its positive content (knowability of God’s existence).
He entered the Society of Jesus in 1893 and was sent in 1903 to the College of Tokat for the Armenians of Anatolia, where he remained until 1907, making in that year a first visit to the rock-hewn churches of Cappadocia, to which he returned from summer 1911 to January 1912.
From 1918 he became professor of Oriental archaeology at the Pontifical Oriental Institute, where he also taught epigraphy and Byzantine institutions. His most substantial work is his two-volume *De l'art pour l'écriture* (Paris 1925–36), divided into four parts and containing 208 plates. This was followed by *Mélanges d'archéologie anatolienne. Monuments préhelléniques gréco-romains, byzantins et musulmans de Pont, de Cappadoce et de Galatie* (in *Mélanges de l'Université de St-Joseph de Beyrouth*, 13 [Beirut 1928]).
As early as 1926 he conducted a thorough study of the Antioch Chalice (q.v.), which some date to the 1st century, while Wilpert considered it a forgery, recognizing in it a product of 6th-century art (*Le calice d'Antioche, Les théories du dr. Eisen et la date probable du calice*, in *Orientalia Christiana* 7 [Rome 1926]). After viewing it directly at the Byzantine art exhibition in Paris in 1931, he confirmed his conclusions (*La voix des monuments*, II, pp. 19–35). Very noteworthy are the two volumes with the evocative title *La voix des monuments. Notes et études d'archéologie chrétienne*, the first appearing in 1930 and the second in 1938. They gather a number of lectures or studies previously published in various journals, but updated and enriched with illustrations. In them is reflected the depth of the author’s learning not only in the fields of iconography and epigraphy, but also in liturgy.