theorist
n. countablen. someone who develops ideas to explain how something works or why something happens. They focus on the rules and logic of a subject rather than the practical work.
n. a person who develops or investigates the underlying principles and abstract frameworks of a particular subject. Often contrasted with a practitioner or an experimentalist.
The theorist spent years developing a new model for the economy.
While the engineers built the prototype, the theorist focused on the mathematical laws that made the design possible.
A political theorist might spend a lifetime analyzing the concept of justice without ever holding public office or participating in a campaign.
From theory + -ist.
Often followed by 'of' to specify a field, such as a 'theorist of international relations'.