Thought experiments have originally been used in physics and philosophy. They are now widely used in various disciplines but remain relatively invisible in the legal domain. Doménech-Pascual explains, nevertheless, that thought experiments are sometimes conducted by lawyers when they interpret legal rules and principles, such as proportionality and equality. Del Mar noted, in particular, that thought experiments can be highly useful in legal practice because they enable ‘institutional kind of pretend play, being very interactive, and thus dialogical or multi-voiced’.

Thought experiments can be valuable in Socio-Legal interview settings for the same reason. When research participants imagine and integrate conditions in a coherent and comprehensive thought experiment, they can enrich our understanding of normative arguments developed in ‘law in the books’. The researcher should ensure the internal validity by accounting for the following conditions: the imagined conditions should be verisimilar and the participants should have expert knowledge. The real-life nature of fieldwork contributes to thought experiments’ external validity.

The major challenge is, however, the reliability of thought experiments. The main point of debate has been whether thought experiments can be misleading; this critique is largely rooted in the idea that background conditions – such as culture and emotions – which are drawn upon by the person conducting the thought experiment, give rise to bias. But this critique seems to be only of limited relevance in Socio-Legal fieldwork. Socio-Legal researchers, particularly those carrying out inductive qualitative work, are often trying to uncover meanings in context. The data created in the thought experiment by participants – in combination with other data after triangulation – can be valuable precisely because they make spontaneous meanings accessible. For example, during my field research in South Korea, I asked senior experts to imagine certain hypothetical extraterritorial human rights regulations of the (i) European Union, (ii) the US and (iii) China that would regulate business activity in his country. One research participant expressed anger about interference in his country’s internal affairs and noted that ‘consumers would not buy products if there were human rights violations' in South Korea. I considered that it was neither necessary nor desirable to question this specific argument during the interview.

The epistemological value of insights gathered through thought experiments constitutes another challenge. Contrary to data gathered through answers to interview questions, thought experiments do not lead to concrete and practical knowledge. Stuart has tried to tackle this issue. He writes that thought experiments provide - at the very least – ‘understanding’ of how social processes and operations interact in context. He relies upon Elgin’s conceptualisation of ‘understanding’, which is - for a large past - ‘knowing’ where ‘a particular fact or finding, concept or value, technique or law’ ‘fits and how it functions in the matrix of commitments that constitute the science.’ In so doing, thought experiments ‘exemplify properties and relations’, generate hypothetical explanations and demonstrate that rival theories can be constructed and lead to different results. Again, generating such rich understanding is at the heart of the socio-legal researcher’s work.