This paper purports to dismiss the symbolic theory of mind via a consideration of the microcircuitry of the brain. In particular, the author argues that the microcircuitry is "stochastic", in that particular neurons do not target particular other neurons, but rather target populations of neurons. Thus any transformation of the neural firing patterns are "stochastic", and a series of such transformations loses the precise, deterministic characteristics that are required for symbolic computing (e.g., addressing).
I find the argument completely unconvincing. The author seems to equate "stochastic" with "uniformly probable." Moreover, the author seems to be unaware of modern information and communications theory. In modern information theory, the major methodology behind the design of codes is "random coding," which was in fact introduced by shannon and is now in common use. Using random codes, it is possible to introduce a coding system that can send signals deterministically through a channel that has arbitrary levels of noise, e.g, it is possible to send clear images from jupiter, even though the channel between Earth to Jupiter is a highly stochastic. The same thing can be said of analog telephony.
In fact, the same can be said of digital information processing, as implemented in analog hardware. Each analog transformation introduces certain stochasticity, but the coding procedure ensures that the probability of the error is vanishly small.
Another serious conceptual error in the paper is the confounding of "separate signalling" with "unconnected." It is entirely possible to communicate signals separate through a channel even though they are distributed across the same set wires. This is called "orthogonal coding."
To make any kind of argument of the sweeping generality that the author is trying to make would require careful argumentation, In particular a mathematical demonstration that it is not possible to do a certain kind of operation. One would want to set up a mathematical model of the purported "stochasticity" of neural connectivity and the study the properties of the channel that this defines. One would want to define a family of codes and study their properties. Only if no reasonable codes are able to give one the properties that one requires (in terms of e.g., space and time) could one draw any kind of conclusion. Such mathematical argumentation is, however, entirely absent from the paper.