pp. 252–253; Lorini 2011, p. 282). In this interpretation of the concept of schema as a medium between the receptivity of the senses and the activity of the understanding, we can see Darjes anticipating an important aspect of Kant’s account. More specifically, Darjes describes here what Kant discusses when he considers concrete, empirical examples of schematising concepts.
Besides this epistemic connotation, the use of ‘schema’ in the philosophical literature of the modern age is still linked to the arts of rhetoric and speech, as it is stated in the Encyclopedie, where ‘schemata’ are seen as instruments of the mnemotechnique, methods used to increase the capacities of memory.
“[…] because for sure our imagination is of great help to our memory, it is not possible to reject the method of schematisms, given that images have nothing extravagant or puerile about them and that they are not applied to things which are not amenable to them.” (Diderot & d’Alembert 1751–1780, transl. L.S.)26←32 | 33→
Differently, namely in reference to biology and physiology, ‘schema’ is used by Ploucquet to indicate the body’s organisation, thus underling once again the function of schemata as a medium between activity and passivity: a body is a material entity provided with an activity giving it organisation: “[…] experience teaches and [the faculty of] reason deduces that bodies are organised in themselves and have a natural capacity to modify themselves in others schemata.” (Ploucquet 1764, par. 399, cap. XVI, transl. L.S.)27
But aside from these rhetorical and biological connotations, the term is used again epistemologically by Johann Nicolas Tetens. In his Philosophische Versuche28, a work which was open on Kant’s desk when he was writing the Critique (as Johann Georg Hamann29 states in a letter to Johann Gottfried Herder on 12th May 1779). Tetens, often called the “German Locke”30, deals among other things with the relation between the soul and the body and the sources and development of human cognition. He follows Darjes’ terminology of a ‘schema perceptionis’31, but regards it as a physical centre of unification of all the data of ←33 | 34→experience, referred to as “material ideas”: “[…] with each manifestation of the soul a certain inner part of our body acts; we can call this part the brain, sensorium commune, the organ of the soul, schema perceptionis or what else.” (Tetens 1777, II 158, transl. L.S.)32
Schemata are regarded as synonyms for sensorium commune or “organ of the soul”, expressions possibly influenced by Charles Bonnet (quoted several times by Tetens) and meant to identify the part of the brain in which ideas are traced and combined. In his L’Essay de Psychologie (1755), Bonnet describes the natural production of ideas from infancy and states: “ideas are nothing but natural signs, and these signs are images traced by objects on the brain.” (Bonnet 1755, VII, p. 13, transl. L.S.)33 Ideas are sensible traces of the objects and it is only through the use of language that abstract thought and universalisation are possible. In this view, the soul can be compared to a musician that plays on the brain (siege de l’ame) but lies in itself beyond any empirical evidence:
“[…] the seat of the soul is a little machine, prodigiously composed and very simple in its composition. […] It is possible to represent this admirable instrument of the operations of our soul with the image of a harpsichord, an organ, a clock or that of another, more composed machine. […] the soul is the musician, which performs on this machine different tunes or judges those that are played and that he repeats.” (Bonnet 1755, Ch IV,9, transl. L.S.)34
However, in order to better understand Tetens’s conception of schemata, whose importance for our purposes lies on his influence on Kant, a deeper inquiry of his doctrine of cognition is needed.
1.3.1 Tetens’s conception of schema
In order to clarify the meaning of the notion of schema in Tetens’s Philosophische Versuche, it is important to focus on his account of the cognitive process.←34 | 35→
In my analysis I will concentrate on three main aspects of his viewpoint: 1) the distinctions among three main faculties; 2) the activity and passivity as characteristics of the cognitive process; 3) the dualism between body and soul, which is expressed by two main claims, namely that there is a correlation between psychological and physical changes and that the soul has an independent and own activity.
Tetens underlines in the opening of the first Essay the distinctions of the three main faculties: “The soul feels, has representations of things, properties and relations and thinks.” (Tetens 1777, I, 1, transl. L.S.)35
These faculties are: Gefühl (the faculty of feeling), Vorstellungskraft (the faculty of representation) and Denkkraft (the faculty of thinking). Feeling is something hard to grasp in itself. It is a complex manifestation of the activity of the soul, which cannot be explained fully: “Then, what is to perceive or to feel? Here I have to confess my inability to explain it. It is a simple manifestation of the soul, which I am not able to divide into more subtle manifestations.” (Tetens 1777, I 170, transl. L.S.)36 Since it is impossible to provide a direct and conclusive characterisation of feeling, Tetens proposes to clarify the characteristics of this basic faculty through an analysis of its objects: impressions, that are, first of all, actual modifications of the subject. We can feel only something that is present and characterised by intensity, duration and extension. Therefore, he agrees, although only partially, with the traditional view of sensibility as a passive faculty:
“What is immediately felt is always, where this modification of the soul could allow itself to be observed, something passive […]. It is never the activity in itself, never the effort itself that we immediately feel; it is a durable consequence of something that is not produced from our spontaneous strength [capacity], but that has been already be produced when it is the object of a feeling; […]” (Tetens 1777, I, pp. 173–174, transl. L.S.)37
This capacity of being affected does not consist only in a mere passivity, but it is at the same time, a kind of activity similar to a reaction. As the body reacts ←35 | 36→to external stimuli, so does the soul as it receives impressions. Each impression modifies the soul, thus leaving a sort of trace, a representation, regarded as a sensible sign of the impressions of the objects affecting our senses:
“[…] these are representations of other objects; modifications, which represent something else and, when they are present, they allow us to see and know not only themselves but also their objects.” (Tetens 1777, I, p. 15, transl. L.S.)38
Since representations are based on impressions, the representational theory of Tetens does not part from the traditional, associative empiricism. However, the associative view of mental activity is only the starting point of his research. Primary sensations represent the objects in the way in which they are perceived (facultas percipiendi). Yet, the soul can exercise an activity through these first representations, since it can reproduce (fantasia) and combine them in new ways (facultas inventiva). Moreover, imagination owns a particular
