Teleonomy is the quality of apparent purposefulness and of goal-directedness of structures and functions in living organisms brought about by natural processes like natural selection. The term derives from two Greek words, τέλος, from τελε-, ("end", "goal", "purpose") and νόμος nomos ("law"). Teleonomy is sometimes contrasted with teleology, where the latter is understood as a purposeful goal-directedness brought about through human or divine intention. Teleonomy is thought to derive from evolutionary history, adaptation for reproductive success, and/or the operation of a program. Teleonomy is related to programmatic or computational aspects of purpose.

Colin Pittendrigh, who coined the term in 1958, applied it to biological phenomena that appear to be end-directed, hoping to limit the much older term teleology to actions planned by an agent who can internally model alternative futures with intention, purpose and foresight:

The concept of teleonomy was largely developed by Mayr and Pittendrigh to separate biological evolution from teleology. Pittendrigh's purpose was to enable biologists who had become overly cautious about goal-oriented language to have a way of discussing the goals and orientations of an organism's behaviors without inadvertently invoking teleology. Mayr was even more explicit, saying that while teleonomy certainly operates on the level of organisms, the process of evolution itself is necessarily non-teleonomic.

Mayr says, 'The existence of complex codes of information in the DNA of the germ plasm permits teleonomic purposiveness. On the other hand, evolutionary research has found no evidence whatsoever for a "goal-seeking" of evolutionary lines, as postulated in that kind of teleology which sees "plan and design" in nature. The harmony of the living universe, so far as it exists, is an a posteriori product of natural selection.^[2]

This attitude towards the role of teleonomy in the evolutionary process is the consensus view of the modern synthesis.^[10]

Evolution largely hoards hindsight, as variations unwittingly make "predictions" about structures and functions which could successfully cope with the future, and which participate in a process of natural selection that culls the unfit, leaving the fit to the next generation. Information accumulates about functions and structures that are successful, exploiting feedback from the environment via the selection of fitter coalitions of structures and functions. Robert Rosen has described these features as an anticipatory system which builds an internal model based on past and possible future states.^{[citation needed]}

In 1962, Grace A. de Laguna's "The Role of Teleonomy in Evolution" attempted to show how different stages of evolution were characterized by different types of teleonomy.^[11] de Laguna points out that humans have oriented teleonomy so that the teleonomic goal is not restricted to the reproduction of humans, but also to cultural ideals.

In recent years, a few biologists believe that the separation of teleonomy from the process of evolution has gone too far. Peter Corning notes that behavior, which is a teleonomic trait, is responsible for the construction of biological niches, which is an agent of selection. Therefore, it would be inaccurate to say that there was no role for teleonomy in the process of evolution, since teleonomy dictates the fitness landscape according to which organisms are selected.^[12][13] Corning calls this phenomenon "teleonomic selection". Additionally, recent research has demonstrated that mutations are not random with reference to their value to the organism.^[14][15] Monroe and colleagues ^[15][16] presented solid evidence that the most important genes undergo fewer mutations. If the phenomenon responsible for making the most important genes undergo fewer mutations remained an enigma, many would easily assume that there is some form of control systems (teleonomy) in the generation of mutations. Assuming this would be incorrect, as the phenomenon responsible for making genes more "protected" from mutations occurs completely automatically, without any teleonomic aspect.^[17]

The Dutch Jewish philosopher Baruch Spinoza defined conatus as the tendency for individual things to persist in existence, meaning the pursuit of stability within the internal relations between their individual parts, in a similar way to homeostasis. Spinoza also rejected the idea of finalism and asserted nature does not pursue specific goals and acts in a deterministic although non-directed way.

In teleology, Kant's positions as expressed in Critique of Judgment, were neglected for many years because in the minds of many scientists they were associated with vitalist views of evolution. Their recent rehabilitation is evident in teleonomy,^{[citation needed]} which bears a number of features, such as the description of organisms, that are reminiscent of the Aristotelian conception of final causes as essentially recursive in nature. Kant's position is that, even though we cannot know whether there are final causes in nature, we are constrained by the peculiar nature of the human understanding to view organisms teleologically. Thus the Kantian view sees teleology as a necessary principle for the study of organisms, but only as a regulative principle, and with no ontological implications.^[18]

Talcott Parsons, in the later part of his working with a theory of social evolution and a related theory of world-history, adopted the concept of teleonomy as the fundamental organizing principle for directional processes and his theory of societal development in general. In this way, Parsons tried to find a theoretical compromise between voluntarism as a principle of action and the idea of a certain directionality in history.

Teleonomy is closely related to concepts of emergence, complexity theory,^[19] and self-organizing systems.^[20] It has extended beneath biology to be applied in the context of chemistry.^[21][22] Some philosophers of biology resist the term and still employ "teleology" when analyzing biological function^[23] and the language used to describe it,^[24] while others endorse it.^[25]

In 2023 the book Evolution "On Purpose": Teleonomy in Living Systems edited by Peter Corning, Stuart Kauffman, Denis Noble, James A. Shapiro, Richard I. Vane-Wright and Addy Pross, it is stated in the introduction that "Teleonomy in living systems is not, after all, only "apparent". It is a fundamental fact of life."^[26]

• Autopoiesis
• Baldwin effect
• Conatus
• Kant's teleology
• Naturalism (philosophy)
• Orthogenesis
• T-symmetry

• Allen, C., M. Bekoff, G. Lauder, eds., Nature's Purposes: Analyses Of Function and Design in Biology. MIT Press, 1998. (ISBN 0-2625-1097-9)
• Mayr, Ernst, The Growth of Biological Thought. Diversity, Evolution, and Inheritance. Cambridge (MA): Belknap Press of Harvard University Press, 1982 : pp. 47–51 (differentiating four kinds of teleology).
• Mayr, Ernst, What Makes Biology Unique?: Considerations on the Autonomy of a Scientific Discipline, Cambridge University Press, 2004. (ISBN 0-5218-4114-3).
• Ruse, Michael Darwin and Design, Harvard University Press; 2004. (ISBN 0-6740-1631-9)

• Merriam Webster definition
• Nonlinearity and Teleology
• Biological Information