The scientific way of reducing complexity is typically an understanding of causes. In modern times, what we call ‘reductionism’ often involves reducing causality to what Aristotle called ‘efficient cause.’ But more recently, several scientists have resurrected versions of Aristotle’s other causes: see Peirce (EP2 selections 9 and 22), Salthe (1993), Ulanowicz (1997, 12-13), Rosen (2000), Deely (2001). Deacon’s (2011) concept of teleodynamics is an update of Aristotle’s ‘final cause.’
One way of distinguishing among Aristotle’s four ‘causes’ is to apply them to the building of a house. The material cause consists of the construction materials such as bricks or lumber, while the formal cause is the Bauplan or design (perhaps represented by a blueprint) that informs the construction process. The building’s form is constrained by the ambient conditions in which the house is built – gravity, climate and so on – so the formal cause can never be made fully explicit in the blueprint, or it would be bigger than the house! The efficient cause is the hands-on, energy-consuming work of the construction crew, and the final cause the purpose for which it is built, namely that somebody should live in it.
Efficient and final causes relate mostly to dynamic functioning or behavior, while formal and material causes relate to embodiment or structure. In terms of process, though, the difference between structure and function is a matter of time scale. A structure can be viewed as a deeply entrenched and consolidated kind of habit. The difference between form and matter is also relative to scale: for instance, cells constitute the matter of which flesh is made, but under the microscope, a cell appears as the form of a system made of molecules.
The final causes of an organism’s behavior can be seen as the role played by its whole life in the larger life of its species. The formal causes, which generally appear at the focal level (Ulanowicz 1997), shape the organism’s role in the life of the current ecosystem.
‘Final’ cause can be thought of as ‘ultimate context’ so long as we do not take ‘ultimate’ in any absolute sense. A scalar level may be ‘ultimate’ to us because it is above any level we are equipped to focus on. This does not imply that there is no higher level, only that whatever higher level there may be is beyond the reach even of speculation. Nor is any final cause necessarily the only final cause of the phenomenon in question. (It is obvious that efficient causes can be plural, but not so obvious with the more vague or general kinds of cause.)
The above is applied to an act or behavior. From a somewhat different point of view, Peirce preferred to both cause and what is caused as ‘facts’ (follow link to rePatch 14 for details).