I.
What Wikipedia says about relational art
Relational art or relational aesthetics is a mode or tendency in fine art practice originally observed and highlighted by French art critic Nicolas Bourriaud.Bourriaud defined the approach as “a set of artistic practices which take as their theoretical and practical point of departure the whole of human relations and their social context, rather than an independent and private space.”[1] The artist can be more accurately viewed as the “catalyst” in relational art, rather than being at the centre.[2]
Source: Wikipedia
II.
What ‘Happenings’ are and what Situationism was
American artist Allan Kaprowcoined the term “happenings” in 1959 to refer to ephemeral, somewhat theatrical, but also participatory, art-related events, many of which were conceived in such a way as to be intentionally open-ended, allowing for improvisation. Artists honored this sense of spontaneity by creating rough guidelines, rather than strict rules or scripts, for participants to follow. The particular social contexts/dynamics and groups of participants (which included the audience members) involved in each happening were integral to the form the events took, causing the same performance to develop differently each time it was carried out. The central belief held by artists involved in creating Happenings was that art could be brought into the realm of everyday life.
The Situationists, a group active from 1957 to 1962, were heavily influenced by Marxist theory, which purported that while living under capitalism, individuals experience alienation and social degradation in their daily lives. They were equally informed by Guy Debord‘s theory of “spectacle,” which states that under capitalism, the mediation of social relations occurs primarily through objects. Wanting to offer solutions toward both these concepts, Situational artists focused on creating works that brought people into direct, immediate encounters and experiences with each other.
For example, they used the strategy of détournement (defined as “turning [preexisting] expressions of the capitalist system and its media culture against itself”) to enact “Situationist pranks,” such as distributing misinformation through false broadcasts, pamphlets, and even church sermons. Another strategy used by the Situationists was the “dérive,” defined by Debord “as a mode of experimental behavior linked to the conditions of urban society: a technique of rapid passage through varied ambiances.” In other words, a dérive was an unplanned journey, like walking through a city’s streets, during which the individual (referred to by Debord as a “psychogeographer,” and also commonly understood as a sort of “flâneur” or romantic wanderer/stroller) allowed himself to be fully aware of, and engaged with, the surrounding environment. They also organized “situations” which were very similar to “happenings.”
Source: https://www.theartstory.org/movement/relational-aesthetics/history-and-concepts/
III. Nineteen-Ninety-Eight and Nicolas Bourriaud‘s book
The French curator Nicolas Bourriaud published a book called Relational Aesthetics in 1998 in which he defined the term as:
A set of artistic practices which take as their theoretical and practical point of departure the whole of human relations and their social context, rather than an independent and private space
He saw artists as facilitators rather than makers and regarded art as information exchanged between the artist and the viewers. The artist, in this sense, gives audiences access to power and the means to change the world.
Source: https://www.tate.org.uk/art/art-terms/r/relational-aesthetics