I have a FreeStyle Libre sensor in my arm. A needle is inserted into the tissue of my left biceps and records the glucose levels of the interstitial fluid there. An app on my wife Anna’s phone records the variation in glucose levels, which she correlates with the food we ate.

Describing this type of change in substance (the substance here being my interstitial fluid) “Monadology” offers insights in the following:

10. I also take it for granted that every created being is subject to change … and even that this change is continual in each one. (Leibniz, 1867; 129)

My glucose levels are subject to constant change; Christmas cake may potentially influence them, but the levels are in constant flux anyway. Further:

13. every natural change takes place by degrees, something changes and something remains; and consequently … there must be a plurality of affections and relations (Leibniz, 1867; 300)

In this example, there is the both the underlying condition of prediabetes, and the elevated glucose levels as the passing change. These have a different set of relationships to me, food and each other, and

14. The passing state, which encompasses and represents multitude within unity … is nothing other than what is called perception (Leibniz, 1867; 130)

How much of this is due to the cake itself, how much other contributory factors and how this can be untangled from the underlying condition, is still a matter of interpretation. And beyond this, the information itself is not knowledge that can be used effectively without being parsed via a summary Anna has made that approximates a healthy glucose range to interpret the numbers generated (see figure 1).

Figure 1: A healthy glucose range

To distinguish between the data recorded by the sensor and what those data mean, Leibniz coined the term “apperception”. Thus, the sensor and the iPhone perceive (in Leibniz’s sense) the glucose level, but it is at the point at which Anna interprets the data that apperception occurs, which “is the consciousness of (or reflection upon) a perception” (Strickland, 2014; 67).

Leibniz next defines the process by which these perceptions are made as appetition.

15. The action of the internal principle which brings about the change or passage from one perception to another may be called appetition. It is true that the appetite cannot always completely reach the whole perception it aims for, but it always attains something of it, and reaches new perceptions (Leibniz, 1867; 130)

In distinguishing between perception and apperception, Leibniz sees perception as being exhibited by substances that are not conscious (1867; 130). However here he ascribes appetition as a change in perceptions that is driven by an aim. Strickland is forgiving of Leibniz’s lapse into teleological thinking, stating that

this is not necessarily a conscious striving: ... in much the same way that a computer script can be said to strive, automatically and unconsciously, to complete each step of a subroutine. (Strickland, 2014; 68)

I argue that a phone app does not display an “aim” in its striving for a whole perception, as “aim” implies conscious intent, which transcends mere programming and requires desire. I’ll therefore distinguish in this discussion between programmed appetition and consciously-driven appetition by modifying the term appetition to “appappetition” when the aims are the result of programming (i.e. appetition by an app), and retain “appetition” for consciously-driven perceptions (and “appetite” to my desire for Christmas cake).

Leibniz immediately contradicts his definition of perception by stating

17. Moreover, we are obliged to admit that perception and that which depends on it cannot be explained mechanically, that is, by means of shapes and motions (Leibniz, 1867; 130). 

that is, material things cannot perceive, which would mean that the ability to perceive is lost once simple substances are combined into more complex ones, but without providing an explanation as to how. Strickland attempts to reconcile this by supposing there may be an intermediate logical step that Leibniz has omitted or that this is simply a self-contradiction, before stating that Leibniz’s consequent arguments follow on from his M14 statement not his M17 statement (Strickland, 2014; 72) and therefore dismisses this statement. A third possibility is that Leibniz has simply failed to apply his developing terminology consistently; if we read “perception” in M17 as “apperception” then Leibniz’s argument is coherent.

Leibniz, G. H (1867) ‘Monadology’ (tr. Hedge, F. H.), The Journal of speculative philosophy, Vol.1 (3), p.129-137

Strickland, L. (2014) Leibniz’s Monadology: A New Translation And Guide, Edinburgh University Press, https://doi-org.ezphost.dur.ac.uk/10.1515/9780748693238