On Some Models of Extended Mechanism in Code Biology.

Barbieri's semantic biology (originally Barbieri 1985) provides an extension of the standard biological ontology, through a new theoretical entity: the code. A specific feature of Barbieri's semantic turn in biology is the use of mechanistic explanations of living systems. This approach allows to work with meaning as the 'new observable' of biology. The relationship between meaning and code is expressed by Barbieri as follows: "[...] meaning is an entity which is related to another entity by a code." (Barbieri 2015, 26). Barbieri refers to the mechanistic model of meaning as an 'extended mechanism'. This work is a follow-up to a previously published paper in which we concluded that the von Neumann probe (and thus the Turing machine) can serve as a "minimal sufficient model of Barbieri's extended mechanism" (Jurková and Zámečník 2023a). We now build on this by connecting the concept of self-reproduction as conceived by Norbert Wiener. Firstly, in order to further explore the 'extended mechanism', but also in an attempt to highlight the importance of self-reproduction as a model of biological processes. We want to highlight the extent to which von Neumann and Wiener collaborated, but also where their understanding and conception of self-reproduction diverge. Wiener, unlike von Neumann, emphasizes that such a machine is "an agency for accomplishing certain definite purposes" (Wiener 2019/1948, 245) and self-propagation "is the creation of a replica capable of the same functions" (Wiener 2019/1948, 245). We suggest that when Wiener views the machine in terms of an 'operative procedure' that enables machine self-propagation, he is implicitly referring to the role of code as thematized in Barbieri's extended mechanism (Wiener 2019/1948, 249). We want to focus not only on classical scientific publications, but also to analyse the personal correspondence between von Neumann and Wiener in which they discussed the issue and how it can change the way we perceive self-reproducing machine.