Doing Science for understanding or changing the world

I recently had this thought that there are two kinds of scientists, or at least two different approaches to getting into science. We either want to understand the world, or we want to change the world.

This is a frequent contention in refereeing both articles and grants. Some will ask you in what way you are describing a new phenomenon or mechanism, while others will ask how your results are likely to change the world.

Physiology is by nature more of a science that tries to understand the world.

Clinical trials is the archetype of science that tries to change the world.

It is by no means necessary to understand the world in order to change it. A true trialist will answer the question of how does your intervention work with a disdainful: "I don't care".

The same goes for the risk factors identified in epidemiological research. They are risk factors because they are associated with some deleterious outcome, not because they are causal, or because we know how it works.

So, the question arises. Why do you do your science?