Function and teleology can be naturalized either by reference to systems with a particular type of organization or by reference to a particular kind of history. As functions are generally ascribed to states or traits according to their current role and regardless of their origin, etiological accounts are inappropriate. Here, I offer a systems-theoretical interpretation as a new version of an organizational account of functionality, which is more comprehensive than traditional cybernetic views and provides explicit criteria for empirically testable function (...) ascriptions. I propose, that functional states, traits or items are those components of a complex system, which are under certain circumstances necessary for their self-re-production. I show, how this notion can be applied in intra- and trans-generational function ascriptions in biology, how it can deal with the problems of multifunctionality and functional equivalents, and how it relates to concepts like fitness and adaptation. Finally, I argue that most intentional explanations can be treated as functional explanations. (shrink)

Two embryonic tissues—the neural crest and the cranial placodes—give rise to most evolutionary novelties of the vertebrate head. These two tissues develop similarly in several respects: they originate from ectoderm at the neural plate border, give rise to migratory cells and develop into multiple cell fates including sensory neurons. These similarities, and the joint appearance of both tissues in the vertebrate lineage, may point to a common evolutionary origin of neural crest and placodes from a specialized population of neural plate (...) border cells. However, a review of the developmental mechanisms underlying the induction, specification, migration and cytodifferentiation of neural crest and placodes reveals fundamental differences between the tissues. Taken together with insights from recent studies in tunicates and amphioxus, this suggests that neural crest and placodes have an independent evolutionary origin and that they evolved from the neural and non‐neural side of the neural plate border, respectively. BioEssays 30:659–672, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

Der erste Teil dieses Buches zeichnet die wissenschaftstheoretischen Auseinandersetzungen um den Reduktionismus ausgehend von den Positionen des Wiener Kreises bis heute nach, wobei sich das reduktionistische Programm als undurchführbar erweist. Wie kann aber der Einheit der Welt Rechnung getragen werden, wenn eine Fülle von Disziplinen scheinbar beziehungslos nebeneinanderstehen? Diese Frage versucht der zweite Teil mit der Grundlegung einer Allgemeinen Systemtheorie zu beantworten. Mit der Einführung eines allgemeinen Systembegriffs können Brücken zwischen den Disziplinen geschlagen werden, ohne die Existenzberechtigung verschiedener Disziplinen in (...) Frage zu stellen. (shrink)