The imaginary entities that make science

In this thesis, I investigate the role unobservables play in scientific explanations, the naturalness of explanations, and the fertility (or developmental potential) of theories. Realist accounts (in particular, the causal-mechanistic account) require unobservables to be real for them to fulfil an explanatory function in theories. Antirealist counts do not assign any particular role to unobservables and marginalise the explanatory power of theories, their naturalness, and their developmental potential as merely of pragmatic interest.