There is a heated debate about what citizen science is and is not. We argue that instead of aiming at a definition of citizen science, we should reflect upon its ethical starting points. Based on our practical experiences with citizen science initiatives, we come up with an ethical framework that consists of two core values (respect and justice), five ethical desiderata (relationship between equals; recognition of each other's capacities, knowledge, and agency; reciprocity; openness for different goals; and openness for different research methods and paradigms) and two fundamental qualities (symmetry and transparency). The desiderata reflect ethically problematic practices, such as the use of citizens by academic scientists as mere sensors, and biases in the existing literature, such as labelling the projects that are initiated and led by citizens as “extreme”. The desiderata are supported by two ethical theories: care ethics and the capabilities approach. The aim of our ethical framework is to stimulate and facilitate reflection upon what needs to be considered when co-creating or assessing a citizen science initiative. Fundamentally, citizen science ought to be a humanizing endeavour unlocking the investigative capacities of humans. The ethical framework is meant to help reflect on this endeavour.
