- For a compendium of perspectives on the province of theoretical biology, click this article's accompanying tab, 'Addendum', or click Theoretical biology/Addendum, which serves as a continuation of the Main Article.
Theoretical biology applies the tools of reason toward the goal of explaining the biological world, in its manifold aspects, through the development of ideas as models, [[Hypothesis|hypotheses] and eventually theories. It thereby distinguishes itself from observational and experimental biology, though without those empirical disciplines, theoretical biologists would have neither inspiration nor information with which to produce their constructs, or to evaluate them.
Charles Darwin's and Alfred Russel Wallace's theory of evolution by means of natural selection, or survival of the fittest, aptly illustrates the co-dependence of information and the tools of reason in producing biological theory.
Scope of theoretical biology
- See also this article's subpage, Theoretical biology/Addendum
If one narrowly defines theoretical biology as the application of the tools of reason in the practice of the science of living systems, then every biologist qualifies as a theoretical biologist. No biologist abandons reason in pursuit of their goals.
Some biologists, however, take it as their major goal to drive themselves to apply the tools of reason to generate ideas about living systems, and consequently find themselves identified as theoreticians. Theoretical biologists aim not to produce observational data or experimental results, but to produce ideas that attempt to explain observational or experimental data, or that attempt to predict novel observational or experimental data as consequences of their ideas. Their ideas may take the form of a hypothetical construct to account for a specific natural phenomenon in living systems, of more elaborate models, or of syntheses of diverse phenomena into revolutionary concepts or theories that have insightful and powerful explanatory and predictive power. The level of formalism may range from the narrative to the mathematical and computational, depending on the nature of the question and the tools of reason employed.
Theoretical biologists emerge in every distinguishable discipline of the science of living systems, and branch beyond traditional biology into philosophy, sociology, economics, and public policy....
Frank Wilczek, a theoretical physicist at MIT and recipient of the Nobel Prize in Physics (2004), might speak for theoretical biologists:
The most exciting thing that can happen is when theoretical dreams that started as fantasies, as desires, become projects that people work hard to build. There is nothing like it; it is the ultimate tribute. At one moment you have just a glimmer of a thought and at another moment squiggles on paper. Then one day you walk into a laboratory and there are all these pipes, and liquid helium is flowing, and currents are coming in and out with complicated wiring, and somehow all this activity is supposedly corresponds to those little thoughts that you had. When this happens, it's magic. 
Using that metaphor, many theoretical biologists could qualify as magicians.
Methods in theoretical biology
In general, the methods of theoretical biologists interact with those of experimental biologists in an iterative feedback process. Observational checks by experimental biologists of the concepts/hypotheses/predictions of theoretical biologists serve a central role for both groups, as the theoretical biologist must critically reevaluate her 'theory' in light of the experimental findings, perhaps finding it necessary to revise her concepts/hypotheses to accord with the experimental results, perhaps inspiring her to ask new questions that expand or redirect her thinking. In turn, the reevaluation/vision process of the theoretical biologists can lead to additional testing by the experimental biologists, requiring them to develop new technologies and enabling them to make new discoveries that enrich the the theoreticians conceptual base, the font of the theoretical biologist's inspiration.
In particular, the methods employed by theoretical biologists include:; conceptualization inspired and guided by...