This document explores the philosophical and linguistic nuances of the concept of reactivity, interpreted not as a mere mechanical reaction but as a deeper capacity or power to respond to external stimuli. The author defines reactivity as "responsiveness," representing the ability to adequately answer someone or something that addresses us or places a specific claim upon us. The text emphasizes that this capacity is closely linked to a process in which a subject is presented with a challenge that necessitates an active stance. A significant element of the reflection is the semantic distinction inspired by the English language, specifically the difference between the terms "responsibility" and "response-ability." This distinction points toward a fundamental human faculty of being in a dialogical relationship with the world and assuming the role of one who is capable of answering current calls and claims from others consciously and directly. Consequently, the text provides a brief yet essential insight into the nature of human interaction and the ethical dimension of the ability to react to the challenges of one's environment.