In his insightful review "Morpheus Unbound: Reimagining the Morphogen Gradient", Arthur D Lander writes:

What distinguishes systems biology from earlier traditions is the tendency to define importance less in operational terms (e.g., necessary or sufficient to produce a behavior) than in terms of relevance to the goals of a system. In making this leap, systems biology inextricably binds itself to teleology (Lander, 2004). Indeed, without the presupposition of goals or purposes, the very notion of “system” itself is hollow.