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(Lat. empirismus, the standpoint of a system based on experience).

Primarily, and in its psychological application, the term signifies the theory that the phenomena of consciousness are simply the product of sensuous experience, i.e. of sensations variously associated and arranged. It is thus distinguished from Nativism or Innatism. Secondarily, and in its logical ( epistemological ) usage, it designates the theory that all human knowledge is derived exclusively from experience, the latter term meaning, either explicitly or implicitly, external sense-percepts and internal representations and inferences exclusive of any superorganic (immaterial) intellectual factor. In this connection it is opposed to Intellectualism, Rationalism, Apriorism. The two usages evidently designate but two inseparable aspects of one and the same theory the epistemological being the application of the psychological to the problem of knowledge.

Empiricism appears in the history of philosophy in three principal forms: (1) Materialism, (2) Sensism, and (3) Positivism.

(1) Materialism

Materialism in its crudest shape was taught by the ancient atomists (Democritus, Leucippus, Epicurus, Lucretius), who, reducing the sum of all reality to atoms and motion, taught that experience, whereof they held knowledge to be constituted, is generated by images reflected from material objects through the sensory organs into the soul. The soul, a mere complexus of the finest atoms, perceives not the objects but their effluent images. With modern materialists (Helvetius, d'Holbach, Diderot, Feuerbach, Moleschott, Büchner, Vogt, etc.), knowledge is accounted for either by cerebral secretion or by motion; while Häcket looks on it as a physiological process effected by certain brain cells. Avenarius, Willy, Mach, etc. subtilize this process so far as to reduce all experience to internal (empirio-criticism).

(2) Sensism

All materialists are of course sensists. Though the converse is not the case, nevertheless, by denying any essential difference between sensations and ideas (intellectual states), sensism logically involves materialism. Sensism, which is found with Empedocles and Protagoras amongst the ancients, was given its first systematic form by Locke (d. 1704), though Bacon (d. 1626) and Hobbes (d. 1679) had prepared the data. Locke derives all simple ideas from external experience (sensations), all compound ideas (modes, substances, relations) from internal experience (reflection). Substance and cause are simply associations of subjective phenomena; universal ideas are mere mental figments. Locke admits the existence, though he denies the demonstrability, in man of an immaterial and immortal principle, the soul. Berkeley (d. 1753), accepting the teaching of Locke that ideas are only transfigured sensations, subjectivizes not only the sensible or secondary qualities of matter ( sensibilia propria, e.g. colour and sound) as his predecessor had done, but also the primary qualities ( sensibilia communia, extension, space, etc.), which Locke held to be objective. Berkeley denies the objective basis of universal ideas and indeed of the whole material universe. The reality of things he places in their being perceived (esse rei est percipi), and this "perceivedness" is effected in the mind by God, not by the object or subject. He still retains the substance-reality of the human soul and of spirits generally, God included. Hume (d. 1776) agrees with his two empiricist predecessors in teaching that the mind knows only its own subjective organic impressions, whereof ideas are but the images. The supersensible is therefore unknowable; the principle of causality is resolved into a mere feeling of successiveness of phenomena; its necessity is reduced to a subjective feeling resulting from uniform association experienced in consciousness, and the spiritual essence or substantial being of the soul is dissipated into a series of conscious states. Locke's sensism was taken up by Condillac (d. 1780), who eliminated entirely the subjective factor (Locke's "reflection") and sought to explain all cognitional states by a mere mechanical, passive transformation of external sensations. The French sensist retained the spiritual soul, but his followers disposed of it as Hume had done with the Berkeleian soul relic. The Herbartians confound the image with the idea, nor does Wundt make a clear distinction between primitive concepts ( empirische Begriffe, representations of individual objects) and the image: "Denken ist Phantasieren in Begriffen und Phantasieren ist Denken in Bildern".

(3) Positivism

Positivists, following Comte (d. 1857), do not deny the supersensible; they declare it unknowable; the one source of cognition, they claim, is sense-experience, experiment, and induction from phenomena. John Stuart Mill (d. 1870), following Hume, reduces all knowledge to series of conscious states linked by empirical associations and enlarged by inductive processes. The mind has no certitude of an external world, but only of "a permanent possibility of sensations" and antecedent and anticipated feelings. Spencer (d. 1903) makes all knowledge relative. The actual existence of things is their persistence in consciousness. Consciousness contains only subjective feelings. The relative supposes the absolute, but the latter is unknowable to us; it is the object of faith and religion ( Agnosticism ). All things, mind included, have resulted from a cosmical process of mechanical evolution wherein they are still involved; hence all concepts and principles are in a continuous flux.


Catholic Philosophy teaches that sense-experience is a source, and indeed the primary source, of human knowledge, but it holds that there are other sources beyond sensations. There is nothing in the intellect that had not its birth in sense; this is one of the generalizations of the School. Moreover, though every intellectual act is accompanied by sensory motion, and especially by some sense representation (phantasma) evoked in the imagination, nevertheless sensation and sensuous representation (phantasma, image) differ essentially from the idea produced in and by the intellect, which is an immaterial, supersensuous and superorganic power or faculty. The theory here proposed may be called empirico-intellectualism since it conjoins a sensuous factor with the purely intellectual or immaterial agency in the genesis of knowledge. Its bases are as follows:

  • Ideas represent the natures or essences of things, not the mere sensuous qualities, the phenomena of things, but the underlying subject and cause thereof, e.g. substance, life, cause, truth, etc.; while ideas of sensuous qualities as such represent them in the abstract and as universal, e.g. light.
  • The mind possesses ideas of things (substances and accidents ) immaterial, invisible, possible, and impossible, etc., e.g. ideas of God, spirit, etc.-- ideas which cannot be formed from purely sensuous presentations or images.
  • we make clear-cut distinctions between the essential and accidental or contingent properties and attributes of things.
  • Every predicate idea represents not a congeries of sensuous qualities, but what the subject is (its essence ), under some particular aspect.

Now none of these peculiarities of the idea can be discovered in any sensation or image, which always represents sensuous phenomena, existent and concrete. Locke's "reflection" and Condillac's "processes of association" will not suffice to transmute sensations into ideas, since these two states are essentially, because objectively (representatively), different. Positivists inadvertently slip in an immaterial agency, whereby indeed they beg the question when they appeal to induction to explain the genesis of knowledge ; the inductive process involves universal abstract principles and logical laws which are constituted of ideas that essentially transcend sensations. The supersensuous character of ideas follows equally from their "extension" or range of applicability. Ideas as representative of essences, are available as predicates, and are the terms whereof absolutely universal principles are constituted. Hence ideas are universal, whereas sensations and images can represent only objects that affect the sensory organs, i.e. individual, physically existing objects. Moreover, ideas represent objects as abstract-- physically abstract, e.g. individual sensible qualities; mathematically abstract, e.g. extension and number; metaphysically abstract, e.g. nature, entity, substance, truth, etc. And indeed unless ideas were of the abstract there could be no science, physical, mathematical, or philosophical ; all these sciences consider their objects apart from concrete individual determinations. No intellectual judgment whatsoever would be possible, since every predicate is a generalized term and hence in some degree abstract. Sensation cannot represent an abstract object; for though the sight, e.g., perceives colour apart from sound, nevertheless

  • no sense can abstract from the subject-matter--from the existence and individuality of its proper object; the eye does not see colour as such and abstracted, but the coloured object physically and individually existing;
  • no sense can abstract from its proper object (its appropriate stimulus or object-quality), nor from its common object (quantity, the extended object);
  • a fortiori, no sense can perceive one dimension of extension or a mathematical point, or things non-existent, or abstract forms like man and humanity.

Nor does the common image suffice to explain the universal idea as Locke and the Herbartians suppose, for the common image, though indistinct, remains always in some way concrete and sensible; since the imagination as primarily reproductive can represent only what the senses have reported. Consciousness attests this; for if the imagination represent e.g. a triangle, it is always of some certain size and shape; it cannot represent a triangle which is neither rectangular, obtuse, nor acute; while the idea of a triangle prescinds from every size or shape. Besides the image there is therefore the thought, the intellectual concept, the latter differing essentially from the former. Hence the common image is not predicable of the individuals distributively because it is still somehow concrete, singular, sensible, material, and represents only quality. Nor can it be predicated as confusedly blending all its inferiors, because the predicate of a judgment is attributed according to comprehension rather than extension. At best, moreover, the image is like to things; the concept is identical with the subject of which it is predicated. According to the empiricists the common image results from a comparison of representations, so that what is common to them, i.e. some pre-eminent quality, stands as the concept. But the intellect would thus have to immediately perceive and compare the images, which is impossible; nor could it form a concept unless a number of sense perceptions and representations of a thing or things of the same species had preceded. We know, however, that we immediately form a concept of a thing, even though perceived but once. Furthermore, in order to form the common image a concept of the object must have preceded; for in order to compare similar things we must previously have perceived their likeness. Now, to perceive their likeness means to perceive some common objective aspect wherein the similar things agree, while differing in other aspects. But this the senses cannot perceive; hence there must precede an intellectual perception of the note of agreement common to the objects represented by the images, i.e. a universal idea must precede the common image. The common image therefore does not precede but follows the common concept, whereof it is a sort of shadow. This is specially so in the case of the productive imagination which re-arranges in new forms previously compared images and hence supposes reflection and judgment, operations which no sense call perform.

Sensism implies scepticism.

  • For if we do not immediately perceive external objects but only our subjective sensuous modifications, then, since these differ with different individuals (e.g. the varying judgments of distance, heat, cold, etc., which varying judgments require intellectual correction whereof the senses are incapable), there could be no certain and objective truth, each individual would be the measure of truth, there would be no objective criterion of certitude, no universal truths.
  • In order to pass from a subjective affection to a knowledge of its object we must employ the principle of causality. Now, in sensism, either the concept of cause is not objective or cause is not perceived at all; therefore the principle of causality is either rejected or is pronounced doubtful. Hence there can be no certitude of the objective existence of things. Hume was but logical when he deduced universal scepticism from the theory of Locke.

Sensism involves the destruction of all science.

  • Science is the knowledge of things in and by their causes; but the senses cannot perceive causes.
  • Positivists claim that by their method the sciences have made wonderful progress, that by employing observation and induction the laws of nature have been discovered. Now, observation of phenomena entails universal ideas whereby the phenomena are classified under groups or species, while induction, to be legitimate and certain, postulates the principle of causality. Therefore the physical sciences suppose physical abstraction ; the mathematical, mathematical abstraction, the metaphysical, metaphysical abstraction (primitive, i.e. direct, and reflective; ontological, logical, psychological ). The negation of universal, necessary, immutable ideas essentially different from sensations means the destruction of even physical science, a fortiori of mathematical and philosophical sciences.

Sensism destroys the foundations of morality and religion. For, as sensists and positivists admit, their theories leave no proof of the soul's spirituality and immortality ; of the existence of moral law, its obligation and sanction in a future life; of the existence of God and His relation to man. Now, history bears witness that these truths are fundamental for man's religious and moral life.

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