Recent Issues

August 2004 Contents

Cover / In This Issue

Society News

Russell's Theory of Cognition

The Russell Papers Find a Home

Bertrand Russell and Orwell's List

1961 Russell Letter to the Times

Boise, Rattlestick Theater, NYC

Russell Peace Foundation Report

from acquaintance to neutral monism:
russell’s theory of cognition

Iva Apostolova

The focus of my paper is the shift in Russell’s view of sensation, memory and imagination in the period 1910-1925 from what is known as the “acquaintance” theory of knowledge to neutral monism. I will argue that the changes in Russell’s views about sensation, memory and imagination are crucial to understanding his epistemology in this period, since he considered the theory of cognitive faculties to be the basis of the theory of knowledge. Russell’s interest in theory of knowledge after 1910 focused on the theory of acquaintance. However, in 1918 Russell realized that the theory of cognition based upon the acquaintance theory faced insuperable difficulties in explaining how the cognitive faculties work. This resulted in the abandonment of key concepts such as the “subject of cognition”, the “cognitive relation between subject and object”, and “sense-data” which eventually led to the adoption of a new theory of knowledge altogether, which he worked out in detail in the period 1918-1925. By investigating the development of Russell’s theory of cognition and the problems associated with it, I hope to show its importance for this major shift from the acquaintance to the neutral monism theories that his later views of the nature of knowledge, judgment, and philosophy were based on.


In 1910 Bertrand Russell’s philosophical interest was directed towards an epistemology based on the analysis of experience. Experience comprises our present experience, or sensations, our past experience, or memories, our imaginings, and our knowledge of properties and relations such as those of logic and mathematics.[1] Our present, past and imaginary experience is described by what Russell called in Theory of Knowledge “acquaintance with particulars”, while the experience of properties and relations is described by the “acquaintance with predicates”.

According to Russell, certain and indubitable knowledge presupposes direct awareness of things without the intermediary of images or of inferences from images to things. Knowledge by acquaintance, as opposed to knowledge by description, provides this direct knowledge of things and is considered the foundation for all other types of knowledge.[2] Of the two types of knowledge by ac-quaintance, acquaintance with particulars, or knowledge of things as they appear to us, is for Russell the most certain knowledge which underpins our knowledge of complex facts and truths.[3] Three cognitive faculties, sensation (which at this time includes perception, introspection, attention, and anticipation), memory, and imagination (which includes hallucination and dreaming) exhaust the types of acquaintance with particulars.[4]

Russell analyzed acquaintance as a two-term relation be-tween subject and object of cognition, i.e., as a direct relation between the mindand matter (sense-data). Although Russell later aban-doned the acquaintance theory and its subject-object structure of knowledge and embraced the theory which states that there is only “one neutral stuff”, he did not give up the idea that the faculties of sensation, memory and imagination are the foundation of know-ledge, and he continued to explore how they relate to each other to build certainty. I beliee that Russell’s theory of the cognitive faculties from 1912-1913, as outlined above, helped him realize that the theory of knowledge by acquaintance has flaws which even-tually caused its replacement with a theory that could better explain cognition.


As we saw earlier, acquaintance with particulars comprises the three main cognitive faculties of sensation, memory and imagination. Russell defined acquaintance with particulars as acquaintance with objects which are “all present to me at the time when I experience them”.[5] However, the sense in which objects are “present”, Russell admited, is troublesome.[6] Not all objects of acquaintance are present in the temporal sense. Temporal presence is problematic for the faculties of memory and imagination. It seems that only the objects of sensation are both present to the mind and present in the sense of being simultaneous with the act of sensation. Objects of memory are in the past, yet somehow they are present to the mind that is acquainted with them; objects of imagination are neither in the present, nor in the past, being imaginary, yet they are somehow present to the imagining mind too.

The difficulty is that the acts of sensation, memory and imagination are all happening now, and so in some sense their objects are all present to them at that moment. But according to Russell’s theory, the objects of these acts are in different temporal relations with the subject, so while the objects of sensation are in the present, the objects of memory are in the past, and those of the imagination are in the imagined (not in the real-time) present, past or future.[7] The problem is that Russell insists that the distinction between the faculties is not based on the nature of their objects but in the temporal relation between object and subject.[8] But whenever the objects relate to the subject they are present to it. Objects of sensation, memory and imagination are all present to the subject of acquaintance and so the temporal relation of subject and object does not account for the distinction between sensations, memories and imaginings.

Another important issue concerns the faculty of memory. According to the acquaintance theory of knowledge, memory plays a pivotal role in extending acquaintance and so foundational knowledge.[9] Memory extends knowledge by acquaintance beyond the “specious present” of sensation and thus releases the subject from the trap of the present moment. In other words, the role of memory, as Russell argued, is to connect our momentary awareness with our past experience of things.[10]

Apart from the general question of how it is possible to be acquainted with the past at all, that is, how we can be directly aware of past objects and events without the mediation of mental entities such as images, the analysis of the faculty of memory which Russell provides in Theory of Knowledge raises other difficulties for his theory. The three types of memory for Russell are “physiological”, “immediate”, and “remote” memory. Physiological and immediate memory are memory by acquaintance, while remote memory is knowledge by description. Physiological memory deals with the most recent past, which nevertheless belongs to the specious present. Immediate memory is also memory of the recent past but its objects do not belong to the specious present. There is something in immediate memory, says Russell, which makes us believe that its objects are in the past and thus are different from sensations or sense-data, even though we are acquainted with them the same way we are acquainted with sensations or sense-data. Unfortunately, Russell does not elaborate on what the role of physiological memory is in his theory of memory, since it virtually belongs to the faculty of sensation. Furthermore, he does not provide a clear account of what distinguishes physiological memory dealing with present objects from immediate memory which deals with recent past objects, and thus does not answer the question of how the objects of memory by acquaintance differ from the objects of sen-sation (whose objects are in the specious present as well) and imagination (whose objects could be in an imagined recent past).

Another difficulty that arises for the relations between the three types of memory is that Russell does not address the issue of how the objects of the three types of memory differ from one another. If the difference is only in their distance in time, then the objects of physiological and immediate memory which deal with the specious present and recent past, can become in due course objects of remote memory. This leads to the conclusion that knowledge by acquaintance could become knowledge by description, which is a far from desirable outcome for Russell’s acquaintance theory.

Yet another problem for Russell’s theory of the cognitive faculties concerns imagination. According to Russell’s definition, “imagination differs from memory and sensation by the fact that it does not imply (though it does not exclude) a time-relation of subject and object”.[11] It seems that what Russell has in mind is that although any imagined object is real, it does not exist in physical time, which means that its temporal status is imaginary. The problem is how the faculty of imagination is distinguished from sensation and memory. Since imagination neither implies nor excludes temporal relations, there is nothing in the nature of the relation of subject and object to distinguish it from memory or sensation.

In Theory of Knowledge, Russell says that the objects of imagination (which include hallucinations and dreams) are usually easily identified because they are unusual and strange compared to the ordinary objects of sensation and memory. Russell acknowledges, however, that this cannot be the basis of distinguishing imagination from sensation and memory because the cognitive faculties are defined by the difference in the relation between the known object and the knowing subject, and not the difference in the objects themselves. Applying Russell’s criterion, I will not be able, for example, to distinguish between a memory of my deceased grandmother and my imaginary vision of her, since both objects are experienced as past.

One conclusion to be drawn from the above is that Russell’s theory of acquaintance with particulars fails to provide a criterion of distinction between the cognitive faculties which it initially aimed for, because it cannot explain their temporal differences.


The period 1918-1919 is one of change for Russell’s epistemology. He realized that the subject-object structure of knowledge which is essential for his acquaintance theory is probably not the steadiest epistemological structure, and certainly not the simplest one. The first important consequence of the abandonment of the acquaintance theory is that Russell no longer believes that we are directly aware of the things around us. Images and inferences of things from images of them, which were rejected as intermediaries between the subject and the object of knowledge in the previous theory, are now acknowledged to be “the only ingredients required in addition to sensation” to build up our cognitive picture of reality.[12]

Secondly, the concepts of “subject” and “object” of cognition which were regarded as separate entities in the acquaintance theory, are now deemed dispensable for the analysis of knowledge. And so, sensation, memory and imagination, with all other “mental occurrences” such as introspection, attention, and anticipation, are no longer conceived as cognitive relations between subject and object. The direct awareness of things provided by sensation is not considered knowledge per se, since knowledge requires habit and the association of images which involve elements foreign to sensation. However, it is important to note that the three faculties of sensation, memory, and imagination were still believed by Russell to be the basis of knowledge. This line of thought began with The Analysis of Mind and persisted throughout the remainder of Russell’s life.[13]


In Russell’s new 1921 “neutral monism” theory of knowledge, perceptual knowledge, which he still regarded as the basis of knowledge, is now explained without appeal to an irreducible duality between a mental subject and material object. The first consequence for the theory of the cognitive faculties of 1921, which drops the theory of acquaintance, is that sensation is now conceived as a part of perception and not as a separate cognitive faculty. Sensation is “extracted [from perception] by psychological analysis”.[14] Perception constitutes the “actual experience” which involves “sensation”, “biography”, “perspective”, “habit”, and application of the so-called “mnemic laws” which connect the present with the past experience.

Perception now comprises the “momentary experience” of things as well as the different perspectives from which each of us experiences them, which forms what Russell calls our “integral experience of things in the environment”.[15] The core of the epistemological analysis, experience, now also includes interpretation, expectation, habit, and belief, which were ascribed earlier to knowledge by description. Sensation is indispensable for the faculty of perception, but it is not the bearer of knowledge. The direct awareness of things provided by sensation is not knowledge, since knowledge requires habit and association of images. The view that sensations are transformed into perceptions is not an isolated consequence of the shift, it actually entails a change of the definition of all cognitive faculties and in this way, of the nature of knowledge in general. The Analysis of Mind is where Russell lays out the details of his new theory of knowledge inspired by neutral monism to which, with certain modifications, he remained faithful for the rest of his life.

The new theory of knowledge was adopted by Russell as a better explanation of how the human cognitive apparatus works and what the nature of knowledge is. However, Russell did not abandon the search for certain knowledge. In the light of this search, the new theory proved to be attractive because, Russell says, it dispensed with the epistemological concepts of “subject”, “object”, and the “dual relation between subject and object” which were at the center of the acquaintance theory, and thus offered a simpler picture of knowledge.

I argue that as a result of the failure of the acquaintance theory to distinguish between the cognitive faculties and between the acts and objects of sensing, remembering, and imagining, the task of Russell’s new theory was rather to explain the common features that make the faculties a part of the “integral experience” of reality. The focus in the new theory of cognition, is shifted from providing a criterion of distinction to exploring the causal mechanisms of the faculties whose operation is explained by a general theory of habit and association of images.

Russell thus changed his mind considerably concerning the faculty of sensation in his shift from the theory of acquaintance to neutral monism. His conviction that having a sensation of something does not mean being in a cognitive relation to an object grew stronger with time. In The Analysis of Mind Russell argues that sensation supplies perception with “data” from the external world but does not amount to knowledge, since knowledge requires an association of images that sensation does not provide.[16] Habit transforms these sensational data into images which can be remembered, associated, imagined, or expected. The “immediate” and “remote” types of memory work through habit, association, and three types of “feeling”. Through the “feeling of familiarity” images of past events are recognized as memories rather than mere imaginations. Memory is also distinguished from imagination by the “feeling of belief” and “feeling of pastness” which accompany our memory-images but not our imagination-images. Since all our memories are images, they are “wholly analyzable into present contents”.[17] In other words, memories represent past events, but are not themselves in the past, and thus the difficulty of having direct knowledge of the past which the acquaintance theory faced is avoided. From Russell’s analysis it follows that what connects the three faculties is the concept of “image”. Images are “occasioned, through association, by a sensation or another image”, and they are also believed to be “copies of sensations which have occurred earlier”.[18] Thus, through images all data coming from sensation, perception, memory and imagination are turned into an “integral experience” of reality.


I hope to have established two main points. First, the three main cognitive faculties of sensation, memory and imagination should be analyzed together, as elements of one theory of the cognitive faculties which plays a crucial role both for Russell’s acquaintance theory and his post-acquaintance philosophy. Second, overcoming the difficulties which the acquaintance theory faced in defining and distinguishing the three cognitive faculties, while keeping the basic epistemological project alive, was for Russell the attraction of neutral monism.

Department of Philosophy
University of Ottawa
Ottawa, ON K1N 6N5


[1] Bertrand Rusell, Theory of Knowledge. The 1913 Manuscript (London and New York: Routledge, 1999), p.33.

[2] Bertrand Russell, The Problems of Philosophy, (Indianapolis: Hackett Publishing Company, 1999), 46; Theory of Knowledge, p. 5.

[3] Bertrand Russell, Theory of Knowledge, pp. 45-47.

[4] Ibid., pp. 53, 79, 100.

[5] Ibid., p. 34.

[6] Ibid., pp. 37-38.

[7] Ibid., pp. 58, 64-66, 70-72.

[8] Ibid. p. 79.

[9] Ibid., pp. 11-12. See also B. Russell, Problems of Philosophy, p. 48.

[10] Bertrand Russell, Theory of Knowledge, p. 12.

[11] Ibid., p. 170.

[12] Bertrand Russell, Analysis of Mind (London, Routledge, 1997), p. 144.

[13] In his article "Russell's Neutral Monism" (Cambridge Companion to Bertrand Russell, Ed. Nicholas Griffin. New York: Cambridge University Press, 2003, pp. 332-371), Robert Tully argues that Russell's mature neutral monist theory was developed not earlier than 1940. This thesis deserves serious consideration. However, for the purposes of my paper, I will accept Russell's claim in The Analysis of Mind that his theory at the time sided with the theory of neutral monism.

[14] Ibid., p. 157.

[15] Bertrand Russell, The Analysis of Mind, p. 157.

[16] Ibid., p. 144.

[17] Ibid., p. 160.

[18] Ibid., pp. 150, 155.