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Synthetic biology and the search for alternative genetic systems: Taking how-possibly models seriously

Abstract

Many scientific models in biology are how-possibly models. These models depict things as they could be, but do not necessarily capture actual states of affairs in the biological world. In contemporary philosophy of science, it is customary to treat how-possibly models as second-rate theoretical tools. Although possibly important in the early stages of theorizing, they do not constitute the main aim of modelling, namely, to discover the actual mechanism responsible for the phenomenon under study. In the paper it is argued that this prevailing picture does not do justice to the synthetic strategy that is commonly used in biological engineering. In synthetic biology, how-possibly models are not simply speculations or eliminable scaffolds towards a single how-actually model, but indispensable design hypotheses for a field whose ultimate goal is to build novel biological systems. The paper explicates this by providing an example from the study of alternative genetic systems by synthetic biologist Steven Benner and his group. The case will also highlight how the method of synthesis, even when it fails, provides an effective way to limit the space of possible models for biological systems.

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Notes

  1. The term “how-possibly explanation” goes back to Dray (1957), who wanted to provide a philosophical account of certain kinds of explanations in the historical sciences. The following presentation does not draw much on the details of Dray’s original account. See Reydon (2012) on how Dray figures in contemporary approaches to how-possibly explanations in the philosophy of biology.

  2. Here Rosenberg seems to follow Dray.

  3. On the importance of this kind of reasoning in evolutionary biology, where actuality is contrasted with nonexistent but nearby possibilities or alternatives that occupy the same “design space”, see Dennet (1995: 102–103, and the subsequent Ch. 5) and Green (2015: 633).

  4. Craver and Darden (2013: 92–94) also mention the importance of engineering or “build it test” as an effective way to further refine scientific understanding of biological mechanisms.

  5. The version of synthetic biology that Benner advocates here (“chemists’ version”) suits well the idea of how-possibly models as alternative design hypotheses because of the built-in contrastiveness, or shared functionality, of the engineered systems. The idea could also be applied to those branches of synthetic biology that try to engineer completely new functions (“things that are not done by natural biology”), but this would require stretching the notion of a how-possibly model somewhat. It is also beyond the scope of this article.

  6. In the case of some xeno nucleic acids, or XNAs, researchers have been able to change the sugar backbone of DNA molecules. However, it is not clear whether these systems can support life. See Schmidt (2010).

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Acknowledgements

I would like to thank Tero Ijäs, Tarja Knuuttila, Kristin Kokkov, and Jani Raerinne for their valuable comments on earlier drafts of this paper.

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Correspondence to Rami Koskinen.

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Academy of Finland project number 272604: Biological Knowledge through Modeling and Engineering.

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Koskinen, R. Synthetic biology and the search for alternative genetic systems: Taking how-possibly models seriously. Euro Jnl Phil Sci 7, 493–506 (2017). https://doi.org/10.1007/s13194-017-0176-2

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Keywords

  • How-possibly models
  • Synthetic biology
  • Alternative genetic systems
  • Possibility
  • Actuality