Through a discussion of the socially extended mind, this paper advances the “not possible without principle” as an alternative to the social parity principle. By charging the social parity principle with reductionism about the social dimension of socially extended processes, the paper offers a new argumentative strategy for the socially extended mind that stresses its existential significance. The “not possible without principle” shows that not only is something _more_ achieved through socially located processes of knowledge building, but also that, and (...) more importantly, what is achieved is something that _would not have been possible without_ social interaction_._ The social parity principle states that the result of an activity achieved via social interaction should be assumed functionally equivalent to a solitary investigation and is characterized by multiple realisability. Contrary to the social parity principle, the “not possible without principle” holds that the result would not have been achieved without the social interaction between (at least) two agents with specific existential needs. The socially extended mind never happens in a void. This means that the "not possible without" principle should be located in real-life, affectively charged, embodied experiences of skilful interactions between agents. This fundamental conceptual change via reference to the “existential necessity” that regulates socially extended processes is necessary in order to effectively lead the socially extended mind to a truly embedded and embodied account. (shrink)