“Sensationalism,” the doctrine that all knowledge is derived from sensations, takes several closely related forms. As a psychological theory it stresses the origins of knowledge and the processes by which it is acquired; it seeks to reduce all mental contents to unitary sensations and has close connections with associationism. It is sometimes, as by its acute but sympathetic critic James Ward, called presentationism.
As an epistemological theory it tends toward the view that statements purporting to describe the world are analyzable into statements concerning the relations between sensations and that this analysis elucidates the meanings of the original statements. It is sometimes regarded as a form of empiricism and adopted with antimetaphysical intentions.
Sensations are usually regarded as occurrences in us, either caused by external objects (Epicurus and John Locke) or not meaningfully attributable to external causes (James Mill and Étienne Bonnot de Condillac). By some they are explicitly likened to feelings or emotions (Anaxagoras and David Hartley), and by others to images (Ernst Mach); the more modern forms, however, probably depend, even if not explicitly, on taking them all as analogous to feelings.
There is a tendency to associate sensationalism with the nineteenth and twentieth centuries, as a development of the work of the empiricists of the seventeenth and eighteenth centuries, but it actually has a long history. A study of its development takes us back to the preSocratics, and although in its modern forms it usually leans heavily on the distinction between sensation and perception, there were views that can be called sensationalist long before the distinction was made (for example, Protagoras held them).
The distinction between sensation and perception is used because it is believed that although perception involves interpretation and, thus, the possibility of error, sensation does not. Sensationalism is therefore sometimes looked upon as the end point of the empiricists’ quest for certainty and a sure foundation for knowledge.
The Greeks had no linguistic means of distinguishing between sensation and perception, but they do not appear to have considered this a serious lack. The preSocratics were apparently interested in perception mainly from the physiological and physical point of view; they wanted to describe processes, which they tended to see as purely mechanical (this is especially true of Empedocles and the atomists), involving the meeting of effluences from the sense organ and the external object.
But Anaxagoras introduced a feature that has some significance for an understanding of sensationalism—namely, the idea that perception involves pain. This facilitates the assimilation of all sensations to feelings referred to below.
PROTAGORAS. Protagoras, accepting the Heraclitean view that all is change or becoming and having concluded that “man is the measure of all things,” found it easy to regard our constantly changing sense experiences as the objects of knowledge and to hold that all the so-called qualities of things, not merely the secondary qualities as the atomists believed, were relative to the perceiver. This turned attention to epistemological questions connected with the nature of perception.
PLATO. Perhaps Plato and Aristotle were primarily reacting against this view of Protagoras in their discussions of perception. Plato’s argument in the Republic is that sense experience does not give knowledge but only opinion, since knowledge must be certain and cannot be of what is constantly changing—that is, sensations or the sensible world.
|nature of perception|
According to some scholars—D. W. Hamlyn, for example—another view can be extracted from the later dialogue the Theaetetus, but this is highly controversial. Protagoras was referring to knowledge of a familiar, everyday sort. The view allegedly to be found in the Theaetetus is that the senses can give us this rudimentary empirical knowledge; they give us direct acquaintance with the outside world and even without interpretation can therefore give us knowledge.
There is no distinction to be made, as far as the sensible world itself is concerned, between what is and what appears. Because sense experience is caused by the external world, it can be regarded as infallible. But this step is suspect both on general grounds and in relation to Plato’s own insistence that the categories of right and wrong are contributed by the mind.
His thought seems to be that if judgment is made by the mind and if saying that something is wrong is making a judgment, then bare sense experience, being prior to judgments of it, cannot ever be said to be wrong. It should, of course, be added that it cannot be said to be right either.
|D. W. Hamlyn|
ARISTOTLE. Aristotle, in attempting to refute the sensationalism of Protagoras, stressed the element of judgment in perception and almost arrived at the distinction between sensation and perception. At the same time he appears to admit an important feature of sensationalism. Each sense has its proper object or special sensible; the proper object of hearing is sound and that of sight is color.
But there are also common sensibles, qualities of objects that are not specially related to any one of the five senses but that are related to the common nature of them all, which he referred to as the common sense. These qualities are, roughly, the primary qualities motion, rest, shape, size, and number.
Because there is a necessary connection between each sense and its special sensible, it is impossible for the senses to make mistakes about them; for example, hearing cannot err about the fact that it is concerned with sound and not color. This, however, does not entail any incorrigibility in the deliverances of the senses as is required by sensationalism. It simply means that each sense is necessarily concerned with its special sensible.
Aristotle’s claims about incorrigibility probably arise, as Hamlyn says, from an unresolved conflict between his view of the senses as both active and passive. (The senses can make mistakes only if they are active and make judgments; as mere passive receptors, they cannot. If we fail to distinguish in this way, we may think of the senses as judging infallibly.) In De Memoria et Reminiscentia Aristotle outlined some principles of association that look forward to later accounts.
EPICURUS. Epicurus, who believed that sense perception is the source of all knowledge, held a causal theory of perception. He did not distinguish between sensation and perception and regarded what were later called sensations as incorrigible because caused.
He was an atomist and attempted a mechanical account of perception. The Stoics opposed this account and again stressed the importance of at least rudimentary judgment in perception. Their conception of phantasiae roughly corresponds to the conception of sensations as images; they held that these were not necessarily veridical although some of them were intuitively certain.
Problems of perception were not central in medieval philosophy except as they bore on the relation between empirical and other varieties of knowledge.
AUGUSTINE. Augustine is important on the subject of perception perhaps only because he saw that it is not meaningful to talk of sensations as either true or false; these terms can be applied only to judgments. He simply assumed that sense impressions correspond to the external world but regarded the knowledge thus obtained as of the lowest kind.
THOMAS AQUINAS. Thomas Aquinas followed Aristotle in his views on perception to the extent of holding that it involves the reception of a sensible form without matter, but this produces a change in the soul, not merely, as for Aristotle, in the sense organ. Sensory images (phantasmata) are received passively, but they are images of external objects. They have the peculiarity that we are not aware of them.
The mind abstracts universal qualities from these and uses them in making judgments. The senses and the intellect are closely connected: Nihil est in intellectu quod non prius in sensu (Nothing is in the intellect that was not first in the senses).
Because our perceptions involve judgments, they may or may not be veridical, but the phantasmata are not appropriately called either. This, with the fact that the phantasmata are images of something, prevented Thomas from being a sensationalist, but he was very close to being one in spirit and utterance.
OCKHAM. Although William of Ockham differed from Thomas in many ways, he also distinguished a sensible and an intellectual element in cognition. Those cognitions that involve only immediate experiences are said to be perfect. Error arises in judgment, but when we are directly apprehending something, we are not in error.
The Seventeenth and Eighteenth Centuries
|The Seventeenth and Eighteenth Centuries|
Sensationalism proper can perhaps be regarded as the product of a steady development of empiricist ideas from the seventeenth century to the nineteenth. Thomas Hobbes is sometimes credited with its inception, but his sensationalism is rudimentary.He did have some conception of the association of ideas and, of course, contributed to the foundations of empiricism.
Largely because of the climate of scientific opinion, involving as it did a growing belief in the importance of observation and experiment, the philosophers of the seventeenth century were much concerned with problems of perception.
They were especially interested in the elimination of errors arising from sense experience and in the attempt to make our knowledge of the natural world as reliable as possible. The rationalists attempted to show that knowledge could be based on indubitable truths of reason, independent of sense experience. The empiricists sought a hard core of indubitable truths involved in sense experience upon which all knowledge could be based.
GALILEO. Galileo Galilei distinguished between primary and secondary qualities and thought that secondary qualities existed only as sensations in us. They are, however, caused by primary qualities in objects, especially by shape and motion.
HOBBES. Under the influence of Galileo, René Descartes, Marin Mersenne, and Pierre Gassendi,Hobbes developed the philosophy of motion into what must be the most thoroughgoing materialism there has ever been. For him all our inquiries must start from sense experience, but there are certain principles—for instance, that motion cannot be understood to have any other cause besides motion—which we know independently of sense experience and upon which other knowledge depends. Nothing exists but matter in motion, so sensations are material changes in us that somehow mediate between motions in the external world and the minute motions of our bodily parts.
Hobbes assumed the existence of external motions causing our sensations; knowledge of these “objects” can come only through sensations. This does not entail the empiricist view that all knowledge is reducible to knowledge of sensations; Hobbes was in general rationalist, for he held that certain truths of reason are essential even for that knowledge of the natural world which depends upon sensation.
LOCKE. Locke’s work marks the beginning of the growth of sensationalism proper, although he was not himself a sensationalist just because he did not develop his particular form of empiricism consistently. His “ideas of sensation” are close to what were later called simply sensations, but his representative theory of perception and his assertion of the existence of substance entail that in spite of explicit claims he relied on knowledge which did not come entirely through sensation.
BERKELEY. George Berkeley attempted to remove this inconsistency in his attack on material substance and representative perception. Whether we view his reliance on God as the unempirical importing of a concept merely for the purpose of filling an embarrassing gap—that is, to allow us to hold that objects continue to exist when no human being is perceiving them—or as the attempt to delineate a concept that is logically necessitated by our experience, Berkeley’s account of ideas brings us very near sensationalism.
There is no talk of external objects that are composed of any material different in kind from what we directly know—that is, ideas. Later sensationalism can be regarded as comparable to Berkeley’s system without God, with all its problems as well as its advantages.
HUME. David Hume continued this development, in one direction by rejecting mental substance, which was retained by Berkeley, as well as material substance. The world for us, as far as we can justifiably say in philosophical contexts, consists of impressions and ideas, and knowledge is of relations between these. Hume was not, however, as great a skeptic as is often alleged.
We have, naturally, certain beliefs—for example, in the external world and in causal efficacy—which cannot be rationally supported.When philosophy fails to provide this rational support, so much the worse for philosophy. If Hume had not been affected by the common view that knowledge implies certainty, he would no doubt have admitted these “natural” beliefs as knowledge and thus have been farther from sensationalism in his official theory than he actually was.
Sensationalism in its fullest sense is best seen in the works of Hume’s lesser-known contemporaries Hartley and Condillac. Hartley’s work was later developed by James Mill, and its most thoroughgoing exponent in the nineteenth century was perhaps Mach.
JAMES MILL. James Mill accepted Hartley’s basic conceptions and developed the psychological side of the theory. Hartley had expressed in terms of vibrations two principal determinants of the strength of association—the vividness of the sensations and the frequency of their conjoint occurrence.
Mill discussed these principles in some detail, without Hartley’s preoccupation with vibrations, contrasting his principles of association with Hume’s and using some rather unsatisfactory arguments for preferring his own. In place of Hume’s contiguity in time and place, causation, and resemblance, Mill put synchronous order and successive order, which include causation as a special case, and vividness and frequency, which include resemblance as a special case.
He went further than Hartley in considering the relation of sensations to the external world; external objects for him are “clusters of sensations.” Most of our beliefs about them depend on sight and sensations of color, with which we associate the other properties we attribute to them.
CONDILLAC. While Hartley was writing in England, Condillac was developing similar ideas in France. He was a disciple of Locke, and his first book was largely an exposition of Locke’s philosophy. In his Traité des sensations, he developed his own psychological theory, largely in opposition to the various current conceptions of innate ideas. He set out to show that all knowledge is “transformed sensation” and does not depend upon anything else, even, as Locke would have had it, reflection.
He examined the nature and power of each of the senses by imagining a statue that has all the human faculties but has never had a sense impression. He then allowed its senses to be activated, one by one and in various combinations, and asserted that the results showed how all knowledge can gradually be constructed. He concluded that people consist of their experiences and that what they perceive is their own mental occurrences.
Unlike Hartley, he did not try to give a mechanical account of these occurrences, being more concerned with psychology than physiology, and he admitted the reality of the soul. He had a considerable influence on the beginnings of British psychological thought through James Mill and J. S. Mill, Alexander Bain, and Herbert Spencer.
Mach and Twentieth-century Empiricism
|Mach and Twentieth-century Empiricism|
Whereas Hartley, Condillac, and the Mills were interested in sensations mainly in relation to psychology, ethics and politics, Mach’s interest sprang from an attempt to provide an analysis of the methods of the physical sciences. His sensationalism was associated with a search for a solid foundation for scientific statements and with a desire to free science of all metaphysics.
He held that only statements which are directly verifiable in sense experience can finally be accepted as conclusions in the sciences. He concluded that all scientific statements are analyzable into statements about the relations between our sensations and that nothing can be said, scientifically, about anything beyond this.
In a sentence reminiscent of James Mill he said, “The world is my sensation.” It follows, also, that the various branches of science do not differ in subject matter but only in their approach to the subject matter, which is—alike for all—sensations; this was the basis of the “unity of science” movement and the logical positivism of the Vienna circle.
|William of Ockham|
Mach’s work was very much in harmony with the spirit of his time, especially in relation to the physical sciences, and has had an important influence on later philosophical thought. He admitted a debt to Berkeley and Hume and a number of his philosophically minded scientific contemporaries.
His idea that the world is composed of “elements” which can be regarded either as sensations or the constituents of physical objects has close connections with Bertrand Russell’s neutral monism and logical atomism, and his description of the aims of science is similar to that of pragmatism and operationism. In one way or another, most empiricist thought about science during the twentieth century has been influenced by his work.
Recent philosophical theories of perception involving sense data or sensa are in the direct line of descent insofar as they stress the mind dependence of sense data, our direct awareness of or acquaintance with them, and the alleged incorrigibility of certain sorts of statements about them. Such theories can be regarded as attempts to refashion Mach’s form of sensationalism in order to avoid some of the obvious objections to it.
|pragmatism and operationism|
Sensationalism and related theories all suffer from one defect, which renders the whole approach suspect; under the heading “sensations” they class together things that it is important to distinguish—for example, such sensible qualities as colors and sounds; bodily aches and pains; desires and emotions; and such feelings as dizziness, anger, and jealousy.
We would not normally be prepared to class all these as experiences, but certain empiricist contentions—for example, that we know colors only through their effects on us—can make it seem superficially plausible to call them all sensations. Just because this blurs the distinctions between various things included under the heading, sensationalism as a general theory gains plausibility.
Toothaches and certain feelings have an air of immediacy and unmistakability that may lead us to suppose that color sensations, since they, too, are sensations, are ultimate and incorrigible data for the construction of a world picture.
I can be certain that I have a toothache, and no one can be better justified than I in asserting or denying this. If color sensations can be assimilated to toothaches, there might seem to be some hope of arriving at incorrigible statements about the external world.
Hence, the importance of the clue afforded by Anaxagoras’s view that perception involves pain. A close examination of experiences of color and other sorts of experience reveals that the necessary assimilation is seriously misleading; moreover, it brings in its train enormous difficulties for an account of science.
On one hand, incorrigibility can be achieved, if at all, only with the loss of the publicity of the statements concerned; on the other hand, it is difficult or impossible to show how scientific problems could ever arise if sensationalism were correct, since there is no reason that any particular combination of sensations should or should not follow any other.
In fact, the word sensation suffers from ambiguities similar to those involved in the word “idea” as used by Locke and Berkeley; as sensation must do even more work than idea, the ambiguities are correspondingly more serious. The view of science that springs from sensationalism, according to which science describes but does not explain, suffers further from insufficient consideration of the nature of description and its relation to explanation and from a failure to appreciate the difficulties involved in the idea of describing sensations.