DEISM is a theological term bearing two accepted meanings.
1. It is the technical name for a particular philosophical doc trine concerning the relation of God to the world. Deism is then contrasted with theism (q.v.), though etymologically the two words are equivalent. Whereas theism asserts God to be continu ously active in the world and in touch with human souls, i.e., to be immanent in, or operative upon, nature and man in respect of providential guidance, revelation and grace, deism limits the divine activity to creation of the world and fixation of its primary collocations. It conceives the world-process to be determined by these alone : the world originally received from its Maker a capacity for self-development, or a delegated autonomy describ able in terms of proximate causes without invocation of further divine intervention. Thus deism is what is popularly called the doctrine of an absentee-God, who, once and for all having wound up the world-machine, has left it to run its course and to work out its self-evolution. In this extreme f orm, deism has seldom been embraced by theological thinkers; it has rather seemed to be an exaggerated conception of the relative independence of the world and its causal nexus. But unless theism asserts somewhat of relatively fixed order and continuity of causal determination in created things, from which the Deity stands "a hand-breadth off" to give free play, so that God is not the sole operative cause in the spheres of physical process and human conduct, it lapses from the doctrine of an immanent God into pantheism. In other words, if theism is to be in earnest with the distinction involved in speaking of God and the world, and is not to adopt Spinoza's identification, expressed in his phrase God or Nature, it must accept so much of deistic tincture as to enable it to assert that. there is a world-order which, however dependent on God, is in some degree independent of Him in that, when once "planted out," it evolves according to the laws of its being, and so pro vides a sphere for His continuous energizing. Thus pantheism and deism are two extremes between which theism is a middle way.
2. Deism is also the received name for a trend of theological thought, not explicitly concerned with the philosophical problem above indicated. The term then has an historical, rather than a technically philosophical, signification; and this is its earlier and commoner meaning. The movement which the word indicates was connected primarily with the relation of revealed religion to natural religion, or the relation of Christian doctrine to theology mediated by reason alone, as exercised on the world and man. It manifested itself chiefly, but not exclusively, in England, and most conspicuously in the i8th century. In fact "deism" is very commonly an abridgment of the phrase "English deism of the i8th century." Deistic thought had, indeed, already appeared in the 17th century; but it was then premature and consequently still born; whereas the movement in the first half of the succeeding century evoked widespread excitement and controversy, and pro foundly influenced theological science.
Deism, as it first emerged, was the natural issue, in theology, of historical causes that operated similarly in other fields of thought. The Reformation had brought individual liberty in re ligion, and toleration had become a politically expedient prac tice. Consequently, variety of opinion found expression, from allegiance to the orthodox theology such as might be called prot estant scholasticism, to the vagaries and "enthusiasms" of indi viduals and sects. The new physical science, progressing rapidly after the Copernican revolution, was presenting an exemplar of certain knowledge, a sound method and criterion of truth. This was the primary quest of deism. It was first prosecuted by Lord Herbert of Cher-bury (1583-1648), the father of English deism, and a contemporary of Descartes. Without denying or repudiating historically "revealed" religion, such as Christianity, Lord Her bert commended a "natural" religion, not transmitted by tradition admitting of corruption, nor accepted on external authority, but demanded and established by reason common to all men, and capa ble of finding universal acceptance. Adopting as certain, because unquestioned in his age, the belief that in all men there is divinely implanted a faculty, such as was commonly called "natural light," comparable to instinct save that it is of the nature of intellection rather than of sensibility, he taught that this rational light is the mediator of innate ideas or "common notions" in which the es sential elements of all true religion are to be found. These are that God exists, that man's duty is to worship Him, that virtue and piety are the essentials of worship, that repentance and retri bution are divinely called for from us, and that there is a future life in which reward and punishment will be meted out. Such, he further held, was the primitive form of religion, from which man kind has been diverted.
As Herbert laid the foundations of deism, in the i 7th century, in so far as its positive and its philosophical aspects are concerned, so also, during the same century, did Charles Blount initiate the negative procedure which became the more conspicu ous characteristic of deism in the later stages of its development. This procedure consisted in criticism of the Scriptures, of re ceived views as to authorship of the sacred books, of miracles, of specific Christian doctrines, and of ecclesiastical history. It has been called negative, because its aim was not so much to commend the certainty and sufficiency of natural theology, of which deism at first asserted revealed theology to be a more or less superfluous republication, as to suggest the doubtfulness of the data, evidences and arguments, on which revealed religion had hitherto been based. The chief writers who, between 1700 and 175o, conducted this attack upon orthodoxy, were Thomas Woolston, Anthony Collins, Thomas Morgan and Thomas Chubb. They were not scholars of the highest order, nor thinkers of more than mediocre ability. Indeed they were silenced by writers better equipped with learning. Nevertheless deism of this nega tive or sceptical kind was not merely the exhibition of temporary unrest or discontent. It was an expression of vague suspicions which developed into critical sciences that, in the succeeding cen tury, effected a revolution in Christian apologetic. In its cham pionship of freedom of inquiry; in search for certainty instead of groundless or disputable opinion; in its insistence on reason as the sole instrument for acquiring and judging of truth, and in its use of the method of doubt, deism may be said to offer a parallel to the Cartesian renaissance in philosophy, and to represent the beginning of modernity in English theology. Hence, even on its negative side, deism is an important movement in the history of theological thought.
This phase of i8th century deism finds its best expression in two works. The first is Christianity not mysterious, by John Toland, in which it is argued that there is nothing in the Gospels that is mysterious, either in the sense of being contrary to reason or in the sense of being above or beyond reason. Toland, from one point of view, upheld the certainty of the natural theology which reason could read, and of the revelation that had been divinely vouchsafed to it. Provided they are allowed to put their own interpretation on the vague and ambiguous word "reason," most persons of common sense, as well as most philosophers, will perhaps nowadays accept Toland's conclusion. If reason include the discovery of actual premises, such as science deals with, it does not provide the infallible natural theology that deism prided itself on having found, and in comparison with which it after wards proceeded to disparage revealed religion. Rather did Bishop Butler, the most considerable critic of the deists, hit the mark in his pregnant dictum, "probability is the guide of life." The other of the two works just now referred to, is Matthew Tin dal's Christianity as old as the Creation; or the Gospel a Republi cation of the Religion of Nature. This book states the case in favour of natural religion more comprehensively than any other of its period: it came to be called "the deist's Bible," and it evoked in especial degree the notice of Bishop Butler and other defenders of revealed religion. The deistic creed, here set forth, is essentially similar to that of Lord Herbert; and natural religion is regarded as consisting in rational knowledge, as contrasted with subjectively caused belief, together with morality. Revelation is restricted to communication of ready-made truth; and the "nat ural" revelation, old as creation, is described as "internal," i.e., as involved or implicated in the constitution of the world and the natures of God and man. Being thus essential or intrinsic, it is an eternal truth of reason, not contingent on historical facts.
If any one of the deists' tenets was more fundamental than another, it was their assertion that revealed religion presupposes natural religion. And this, though it was for the most part over looked or evaded during the i 9th century, may be regarded as their lasting contribution to theological thought. Unfortunately their conception of the content of natural theology, and of the rational grounds on which they supposed it to be infallibly based, involved a priori assumptions which, shortly after deism found its completed expression in Tindal, were demolished by Hume, and later by Kant. Genetic sciences as yet scarcely existed ; evo lution or development was as wanting from the stock of i8th century ideas as it was paramount in the succeeding century. So the deists worked with static ideas; and some of the assumptions, which to them seemed self-evidept truths, came to be found in consistent with facts. Human nature and reason are evolved prod ucts; and reason as innate lumen naturale, to which, the deist thought, a just God must reveal Himself perfectly and clearly from the first, never existed. It may be observed, however, that none of those free-thinkers held the kind of deism that was here first described, but rather repudiated it as "atheism." See Leslie Stephen, History of English Thought in the r8th century, Vold. (1876 and 1902) and the bibliography therein. (F. R. T.)