JTW's Evolutionary Origins - Author: Wood, John T.

The Deterministic Sciences Meet the Historically Contingent Sciences

One of the most interesting features of OOL studies are the interfaces between the hard sciences of physics and chemistry and, the scientific discipline of biology.

While chemistry and physics provide the theoretical foundations for understanding biological structure and function, they are inadequate to fully explain biological phenomena without the introduction of supplementary concepts.

Chemistry and Physics are largely formulated as ahistorical sciences, where the phenomena can be understood by examining existing elements, and their relations, with no consideration of how they came to be; it is only necessary to know their current states.

Biology, especially as it pertains to evolutionary phenomena, is a historical science where knowledge of the systems path through prior states is necessary to understand the nature of it's current state.

Within each of these sciences, processes can be divided into two types: path functions, where the outcome of an event depends on a specific sequence of steps leading to the final state (i.e. the path taken is important); and state functions which are independent of the sequence of steps leading to the final state (i.e. the particular path is not important).

In the Physical Sciences, mechanistic explanations prevail at the level of individual events and theories are designed to predict deterministic outcomes for these events, regardless of their prior history.

When the number, or population, of events under consideration grows to large for the practitioner to work with, physical theories shift to a statistical mode of description that builds off the deterministic mechanical analysis of individual events within the population under consideration.

The statistical behavior of a population may stablize, allowing the the collective population to be considered as a stable element in a higher level mechanical analysis, which leads to the prediction of deterministic outcomes.

As we ascend the scale of phenomena from nano- to micro- to macro-, we move back and forth between deterministic explanations of individual phenomena and statistical explanations of collective phenomena.

In the Chemical sciences, the main focus of study is upon the statistically dominant reaction pathways available to the reactants under the prevailing conditions of the reaction system.

Side reactions, especially low-propensity reactions, are usually neglected or considered to be inconviences that lower the yield and purity of the desired product(s).

There are two main theoretical branchs of chemistry: Thermodynamics and Kinetics.

Thermodynamics is formulated in terms of state functions that are path-independent, whereas Kinetics is formulated in terms of path-dependent functions.

Chemistry is generally dealt with in a statistical fashion due to the numbers of molecules involved, but it is generally understood (or assumed) that deterministic mechanisms are at work on the molecule to molecule scale.

Most systems studied by chemists are relatively simple systems with correspondingly small solution spaces for the outcome.

Biology, in addition to being rooted in the hard sciences, is a historical science, that is, it's outcomes are path dependent.

"Nothing in Biology Makes Sense Except in the Light of Evolution"

Biology, while sharing deterministic mechanical and statistical relations akin to those of chemistry and physics, is also a science of evolutionary contingencies, where low-propensity events come to have a dominating influence over future events, and become necessary and essential to understanding how biological phenomena come to be.

Is Biology "reducible" to Chemistry and Physics?

For many the goal is to reduce biology to chemistry and physics, via biochemistry and biophysics.

While undistorted equivalence transformations between scientific descriptive systems is desirable, it appears that going from biology to chemistry and physics requires additional conceptual frameworks to bring this about.

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