It is traditionally contrasted with metaphysical naturalism, which views nature as lacking design or purpose. In the first case, form is defined by function, in the second, function is defined by form. Teleology would say that a person has eyes because he has the need of eyesight, (form follows function), while naturalism would argue that a person has sight simply because he has eyes, or that function follows form (eyesight follows from having eyes).
In European philosophy, teleology may be identified with Aristotelianism and the scholastic tradition. Most theology presupposes a teleology: Design in nature can be used as a teleological argument for the existence of God. Aristotle's analysis of four causes speaks of a material cause, efficient cause, and formal cause but all these serve a final cause.
Imagine not being able to distinguish the real cause from that without which the cause would not be able to act as a cause. It is what the majority appear to do, like people groping in the dark; they call it a cause, thus giving it a name that does not belong to it. That is why one man surrounds the earth with a vortex to make the heavens keep it in place, another makes the air support it like a wide lid. As for their capacity of being in the best place they could possibly be put, this they do not look for, nor do they believe it to have any divine force, but they believe that they will some time discover a stronger and more immortal Atlas to hold everything together more, and they do not believe that the truly good and "binding" binds and holds them together." [Plato, Phaedo 99bc]
Similarly, Aristotle argued that Democritus, proponent of the atomic theory, was wrong to attempt to reduce all things to mere necessity, because such thinking neglects the purpose, order, and "final cause" that causes the necessity:
Democritus, however, neglecting the final cause, reduces to necessity all the operations of nature. Now they are necessary, it is true, but yet they are for a final cause and for the sake of what is best in each case. Thus nothing prevents the teeth from being formed and being shed in this way; but it is not on account of these causes but on account of the end...." [Aristotle, Generation of Animals V.8, 789a8-b15]
Hence Plato and Aristotle agreed that all lesser causes were in the service of an ultimate good while Democritus or Lucretius were supporters of what is now often called metaphysical naturalism, or accidentalism:
In the various neo-Hegelian schools - proposing a history of our species some consider to be at variance with Darwin, with the dialectical materialism of Karl Marx and Friedrich Engels and with what is now called analytic philosophy — the point of departure is not so much formal logic and scientific fact but 'identity'. (In Hegel's terminology: 'objective spirit'.)
Individual human consciousness, in the process of reaching for autonomy and freedom, has no choice but to deal with an obvious reality: the collective identities (such as the multiplicity of world views, ethnic, cultural and national identities) which divide the human race and which set (and always have set) different groups in violent conflict with each other. Hegel conceived of the 'totality' of mutually antagonistic world-views and life-forms in history as being 'goal-driven', that is, oriented towards an end-point in history. The 'objective contradiction' of 'subject' and 'object' would eventually 'sublate' into a form of life which leaves violent conflict behind. This goal-oriented, 'teleological' notion of the 'historical process as a whole' is present in a variety of 20th Century authors, from Lukács and Jaspers to Horkheimer and Adorno.
Against this, Alasdair MacIntyre has argued that a narrative understanding of oneself, of one's capacity as an independent reasoner, one's dependence on others and on the social practices and traditions in which one participates, all tend towards an ultimate good of liberation. Social practices may themselves be understood as teleologically orientated to internal goods, for example practices of philosophical and scientific enquiry are teleologically ordered to the elaboration of a true understanding of their objects. MacIntyre's book After Virtue famously dismissed the naturalistic teleology of Aristotle's 'metaphysical biology', but he has cautiously moved from that book's account of a sociological teleology toward an exploration of what remains valid in a more traditional teleological naturalism.
Science concerns itself with physical causality and is well able to function within the bounds of naturalism, indeed, it has frequently to counter appeals to undemonstrable modes of causality. Yet teleological ideas still find refuge in the unpenetrated beginnings and endings of things.
Teleological arguments in the field of chemistry have once again often centred around the fitness of materials to form the complex molecular bonds of life. For example, Lawrence Joseph Henderson, an American bio-chemist, advanced such a view in the early 20th century.
Biology has always been susceptible to teleological thought, even after Darwin proposed survival as the only observable final good. Driesch, for example, presented a modified vitalism in which an Aristotlean (or Kantian) entelechy drove embryonic development. Contemporary accounts of teleology within biology are heavily influenced by Larry Wright's etiological account, which seeks to supply a definition of "function" that can be applied to natural phenomena as well as human constructions such as a hammer. Most contemporary accounts of teleology follow Wright. (Ruth Millikan for instance). Others, however, such as Godfrey-Smith and Ernst Mayr, object to any such theory, preferring naturalistic accounts of teleology.
Julian Bigelow, Arturo Rosenblueth, and Norbert Wiener have conceived of feedback mechanisms as lending a teleology to machinery. Wiener, a mathematician, coined the term 'cybernetics' to denote the study of "teleological mechanisms," . Cybernetics is the study of the communication and control of regulatory feedback both in living beings and machines, and in combinations of the two.
In recent years, end-driven teleology has become contrasted with "apparent" teleology, i.e teleonomy or process-driven systems.
For a very detailed discussion of the recent resurgence of teleology in natural science, see Barrow and Tipler (1986). Their work includes: