The call for action has taken centre-stage in education for sustainable development. We explore the potentials of phronesis as a unifying and action-oriented concept involving ethical thinking, practical judgement and reflection. Phronesis or practical wisdom, combines a web of capacities based on both theoretical and practical knowledge applied to the particulars of a situation. The analysis uses the distinction of thick and thin concepts, and how evaluative as well as epistemic components of a concept may offer new aspects on the notion of action. In education that provides situations for students to participate and to see themselves as subjects, Is, students get the opportunity to practice how to deliberate and may develop intellectual virtues to some degree and respond to the call of the planet to take action. Linda Zagzebski’s historical exposé of the two greatest ideas in the Western tradition, concerns the epistemic and the moral, what the human mind can grasp, the universe and itself. The ideas bear resemblance to the two educational paradigms that Gert Biesta refers to as the cultivation paradigm and the existential educational paradigm. The transmethodological method allows for the nesting of concepts to provide new insights to the notion of action in ESD.