Leibniz' Mill Analogy Disproved?

Leibniz, in the Monadology, gives the famous analogy of the mill as a metaphor for the brain:

17. Moreover, it must be confessed that perception and that which depends upon it are inexplicable on mechanical grounds, that is to say, by means of figures and motions. And supposing there were a machine, so constructed as to think, feel, and have perception, it might be conceived as increased in size, while keeping the same proportions, so that one might go into it as into a mill. That being so, we should, on examining its interior, find only parts which work one upon another, and never anything by which to explain a perception [emphasis mine here--wh]. Thus it is in a simple substance, and not in a compound or in a machine, that perception must be sought for. Further, nothing but this (namely, perceptions and their changes) can be found in a simple substance. It is also in this alone that all the internal activities of simple substances can consist. (Theod. Pref. [E. 474; G. vi. 37].)

Now we have the metaphor of the mill done for real, in the virally expressed GCaMP3 mouse hippocampus of the brain.

See video link here, and abstract below:


Long-term dynamics of CA1 hippocampal place codes

Yaniv Ziv, Laurie D Burns, Eric D Cocker, Elizabeth O Hamel, Kunal K Ghosh, Lacey J Kitch, Abbas El Gamal, Mark J Schnitzer

Nature Neuroscience (2013) doi:10.1038/nn.3329 Received 29 October 2012 Accepted 09 January 2013 Published online 10 February 2013 Corrected online 11 February 2013

Using Ca2+ imaging in freely behaving mice that repeatedly explored a familiar environment, we tracked thousands of CA1 pyramidal cells' place fields over weeks. Place coding was dynamic, as each day the ensemble representation of this environment involved a unique subset of cells. However, cells in the ~15–25% overlap between any two of these subsets retained the same place fields, which sufficed to preserve an accurate spatial representation across weeks.


So, it seems that Leibniz was wrong, in part. He forgot that a skilled mill engineer could likely tell something about what the mill's activity was focused upon, to some degree, just by observing the activity of its components. Thus, mind reading might be possible, in the sense of knowing something of what the mouse is experiencing from observing the patterns of memory cells which are activated as the mouse visits the different sections of its enclosure.

What we still cannot tell is what it is like to be the mouse, even if we have an inkling of what topics are within the focus of its attentions. In that regard, at least, Leibniz is still right about perceptions.

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