The concept of "vitalism" has been traditionally associated to pseudoscience, a metaphysical concept away from any empirisism. It is often referred to as the action of a "vital force" or "entelechy" proper to organic matter, that governs and directs living processes. However, Ortega y Gasset (see the post below) defines vitalism as "any biological theory that considers organic phenomena irreductible to physico-chemical principles" and states that it can be conceived from two radically different points of view: a) the assumption of a special form of entelechy or "vital force" distinct from physicochemical forces, or b) a rigurous empiric approach to study vital phenomena in the feral peculiarity they manifest, without assuming any mysticism, but avoiding a dramatic reduction to its physical properties.
In light of this distinction it is worthwhile to recall some concepts such as "emergence", a core notion of complex systems. "Emergent properties" are not properties of any component of the system, but of the system as a whole. Examples vary from "hurricanes" to "swarm intelligence" and "consciousness". As opossed to pseudoscientific vitalism, emergence is not restricted to organic matter, but is proper to systems.
Teleonomy is a term coined for the "apparent purposefulness" of living processes, as contrasted from "teleology", a concept that indicates intention of an external agent. We may well accept the distinction, although it is a common vice in scientist to confuse them, but an important question still remains: what is the biological process that lets us, as observers, to recall teleonomy?
Ernst Mayr (1965) have said: "It would seem useful to rigidly restrict the term teleonomic to systems operating on the basis of a program of coded information", but do we need to recall "information" to explain "apparent purposefulness"? It seems to me that to invoke "coded information" is as finalist as invoking an entelechy's "intention", so it would not be an acceptable biological answer.
It seems that our mechanicist tradition has forced us to reduce causes to the physico-chemical conformation, rather than to the organization. This reductionism has not only been uncapable of explaining biological phenomena, but has kept biologists in an Aristotelian "formal cause" reasoning, where genetic information is the entelechy able to determine the parts and relationships within organisms, thereby equating the metaphysical and organisational forms of vitalism.
A systemic answer to the "apparent purposefulness" dilemma can be envisioned by recalling the ontogenic phenotype/ontogenic niche relationship (the particular manner of living of an organism of a certain lineage). So when an investigator is observing an organism she recognizes a particular behaviour and can visualize a response for a given situation: she is bringing forth an operational congruence (adaptation) of the organism with its niche, that although pertains to the virtual domain of her observations, would seem to respond to an "apparent purposefulness". However, the organism is free to display behaviours distinct from those expected by the observed, as long as it maintains its adaptation, so the "apparent purposefulness" is only an observational artifact proper to the mind of the investigator accostumed to observe configurations.