I seek to evaluate the scope of philosophical discussions about the status of memory in relation to the history of the memory trace theory. After a brief review of the conditions for the emergence of memory traces as a scientific concept, I focus on the crucial period before the 1960s, a period of development of the epistemologically determinant axes of the philosophy of mind. I hope to put into perspective the current debate on memory traces and to improve the understanding of its evolution, between brain theory and philosophy.

Based on the Greek idea of typos, Western culture early on used two complementary images to express the embodiment of memories: memory as wax tablets on which information is recorded, and memory as store or inventory. With these models, the discourse on memory moved towards increasing ‘embodiment’ or ‘cerebration,’ in intention at least, given the lack of instrumentation and operative brain theory. From the Greek metaphors onwards, the idea that memory must be associated with a physical change runs through the entire history of Western thought, from the clinical observations of Renaissance physicians to the cerebral physiology of the Enlightenment.

But this dynamics of the rejection of organic memory is not sufficient to understand the emergence of human memory as a scientific object. It is really in the late 19th century that the science of memory of the individual man begins. In the field of knowledge, the situation of memory changes both in writings and in practice. Human memory could no longer be either a more or less noble element within a general philosophy of mind, or an intellectual property that could be manipulated to improve it. It could not be included, more or less harmoniously, in an elegant but speculative philosophical psychology. Memory must be constituted as an object whose study is in itself a sufficient purpose, that is to say as a true object of science, explored by various emerging disciplines: psychology, psychiatry, neurology. Although specialized writings on memory were previously very numerous, specific strategies to elucidate cerebral memory functions are clearly identifiable only in the 19th century. Thus, emerging experimental psychology, which initially focused mainly on the perceptual issues, organized around memory while psychiatrists developed taxonomies of clinical amnesia, and biologists developed new psychophysiological hypotheses. Frantically observed, experienced, dissected, memory is naturalizing. Whatever the age of the physiological theories of memory and their metaphors, the history of the science of memory, understood as a scientific object worked on by different competing communities, hardly spans one and a half centuries (see Dupont 2005).

But from a philosophical point of view, the fundamental issues remain as a legacy.

In this regard, neuroscience seems to manage the issues raised by classical philosophy, moving in the direction of traditional solutions, while being more or less aware of the difficulties. The classic mind-body problem had left out some insurmountable complications, at least in a naturalistic perspective. While maintaining two distinct ‘substances’ left the mystery of their interaction intact (unless one adopted the dualist positions of the electrophysiologist John Eccles (Eccles 1994), parallelism denied interaction without explaining the apparent strict correlation between physical and mental phenomena (now dramatically evidenced by functional brain imaging techniques). While rejecting any form of dualism, cognitive neuroscience has unequivocally chosen the world of representations. Mental phenomena are postulated as a special class of natural phenomena, accessible to natural science and definable by their causes and their effects. The challenge is to show how this causal role is exercised, i.e., to describe how the neurophysiological mechanisms perform these causal functions and how physical phenomena underlie mental phenomena. The mind is a patchwork of emergent properties of brain function. Even the consciousness that accompanies certain mental activities seems to emanate from the brain functioning.

In this perspective, whatever the nuances of the positions taken, the mind keeps its ontological reality, but in some way functionally “disappears” in the brain. To say that all the laws of nature (biological, physical, social) are logical consequences of physical laws (and thus explain inorganic processes) may not eliminate the mind, but amounts in practice to considering the mind as a sub-species of physics, an epiphenomenon. It is therefore true that cognitive neuroscience is often causalist, reductionist, and materialist, and that these positions often seem the least doctrinal and the most natural for biologists committed to the “trace program.”

To understand the role of memory in the logical construction of the world, one should remember that the latter faces at least two problems: the choice of the basic elements from which everything else is built, and the choice of basic relations, that is to say, the logical forms by which the shift from one level to another occurs. According to Rudolf Carnap, the basic elements are the elements of experience: it is a phenomenal basis consisting of statements about perceptual experiences. Carnap describes several basic relations: the similarity of parts and the recollection of similarity, referred to as Er (= Errinerung, ibid., § 78). By recollection, Carnap does not intend to introduce the reproduction of an already faded experience, but the retention of an immediately preceding experience, a simple relation to something that happened a short time before, for example a perception. But Carnap cannot and does not want to say more about the nature of what is retained. All he cares about is that any proposition on any object of knowledge can thus be reduced to a proposition on the basic elements, with recollection of similarity as the basic and sufficient relation. Quality classes are the first elements of elementary experiences, that is to say, the qualities of sensations. With the help of these spatio-temporal qualities, the world of physical objects can be built, and then more complex objects can be described, particularly psychological and mental objects. The Aufbau is based upon logical and formal aspects of the theory of classes, the theory of relations, and in empirical terms, upon a solipsistic basis (knowledge is primarily subjective). The system of the constitution is formed at the base of a fundamental first relationship, recollection of similarity, and by the first elements of experience. To all that must be added the choice of a basic language: logic. Science does not deal with content but with the form. It is only in this sense that experiences can be seen as the basis of the system. Carnap distinguishes two kinds of descriptions: descriptions of properties and descriptions of relations, and the Aufbau only contains the latter. This description of relations is purely structural.

It is clear that under these conditions the elementary experiences differ from qualitative factors in a very psychological way. Elementary experiences have no properties. Propositions on these experiences can be united by their relationships and not by their qualitative determinations. For example, visual and acoustic perceptions are not personal experiences, but are first sorted by their comparison. Similarly, it is clear that memory should not be considered as a function in a psychological sense, but as a logical relationship (recollection of similarity).