The social world is made of meanings. People act on what things mean to them.
Understand actions from the inside. Aim for interpretation, not prediction.
What does this mean to the people involved?
Key thinkers: Max Weber, Alfred Schutz, Clifford Geertz
The longer story
Interpretivism starts from a simple observation: people, unlike rocks, act on the basis of what things mean to them. To understand why someone paints, protests or goes to the opera you need their reasons, not only their behaviour. Weber called this Verstehen, understanding from the inside.
The researcher's job is to interpret those meanings and set them in context, often through interviews, observation and close attention to language. Findings are judged on depth and credibility, not on whether they predict anything. It is the default position for a great deal of qualitative research, often without being named.