Evil, in a large sense, may be described as the sum of the opposition, which experience shows to exist in the universe, to the desires and needs of individuals; whence arises, among humans beings at least, the sufferings in which life abounds. Thus evil, from the point of view of human welfare, is what ought not to exist. Nevertheless, there is no department of human life in which its presence is not felt; and the discrepancy between what is and what ought to be has always called for explanation in the account which mankind has sought to give of itself and its surroundings. For this purpose it is necessary (1) to define the precise nature of the principle that imparts the character of evil to so great a variety of circumstances, and (2) to ascertain, as far as may be possible, to source from which it arises.
With regard to the nature of evil, it should be observed that evil is of three kinds -- physical, moral, and metaphysical.
Physical evil includes all that causes harm to man, whether by bodily injury, by thwarting his natural desires, or by preventing the full development of his powers, either in the order of nature directly, or through the various social conditions under which mankind naturally exists. Physical evils directly due to nature are sickness, accident, death, etc. Poverty, oppression, and some forms of disease are instances of evil arising from imperfect social organization. Mental suffering, such as anxiety, disappointment, and remorse, and the limitation of intelligence which prevents humans beings from attaining to the full comprehension of their environment, are congenital forms of evil each vary in character and degree according to natural disposition and social circumstances.
By
moral evil are understood the deviation of human volition from the prescriptions of the moral order and the action which results from that deviation. Such action, when it proceeds solely from ignorance, is not to be classed as moral evil, which is properly restricted to the motions of
will towards ends of which the
conscience disapproves. The extent of moral evil is not limited to the circumstances of life in the natural order, but includes also the sphere of religion, by which man's welfare is affected in the supernatural order, and the precepts of which, as depending ultimately upon the
will of God, are of the strictest possible obligation (see
SIN). The
obligation to moral action in the natural order is, moreover, generally believed to depend on the motives supplied by religion; and it is at least doubtful whether it is possible for moral obligation to exist at all apart from a supernatural sanction.
Metaphysical evil is the limitation by one another of various component parts of the natural world. Through this mutual limitation natural objects are for the most part prevented from attaining to their full or ideal perfection, whether by the constant pressure of physical condition, or by sudden catastrophes. Thus, animal and vegetable organisms are variously influenced by climate and other natural causes; predatory animals depend for their existence on the destruction of life; nature is subject to storms and convulsions, and its order depends on a system of perpetual decay and renewal due to the interaction of its constituent parts. If animals suffering is excluded, no pain of any kind is caused by the inevitable limitations of nature; and they can only be called evil by analogy, and in a sense quite different from that in which the term is applied to human experience. Clarke, moreover, has aptly remarked (Correspondence with Leibniz, letter ii) that the apparent disorder of nature is really no disorder, since it is part of a definite scheme, and precisely fulfills the intention of the Creator; it may therefore be counted as a relative perfection rather than an imperfection. It is, in fact, only by a transference to irrational objects of the subjective ideals and aspirations of human intelligence, that the "evil of nature" can be called evil in any sense but a merely analogous one. The nature and degree of pain in lower animals is very obscure, and in the necessary absence of data it is difficult to say weather it should rightly be classed with the merely formal evil which belongs to inanimate objects, or with the suffering of human beings. The latter view was generally held in ancient times, and may perhaps he referred to the anthropomorphic tendency of primitive minds which appears in the doctrine of metempsychosis. Thus it has often been supposed that animal suffering, together with many of the imperfections of inanimate nature, was due to the fall of man, with whose welfare, as the chief part of creation, were bound up the fortunes of the rest (see Theoph. Antioch., Ad Autolyc., II; cf.
Genesis 3 and
1 Corinthians 9). The opposite view is taken by
St. Thomas (I, Q. xcvi, a. 1,2).
Descartes supposed that animals were merely machines, without sensation or consciousness; he was closely followed by Malebranche and Cartesians generally.
Leibniz grants sensation to animals, but considers that mere sense-perception, unaccompanied by reflexion, cannot cause either pain or pleasure; in any case he holds the pain and pleasure of animals to be parable in degree to those resulting from reflex action in man (see also Maher, Psychology, Supp't. A:, London, 1903).