Final answer:
Jan, who thinks knowledge comes from observation, is likely an empiricist, which is a philosophical stance emphasizing sensory experience as the source of knowledge.
Step-by-step explanation:
Jan believes that all knowledge is acquired through careful observation, which indicates that Jan is probably an empiricist. Empiricism is the philosophical belief that knowledge comes from sensory experience and is subject to revision and falsification. Notable empiricists like John Locke and David Hume assert that the mind starts as a blank slate (tabula rasa) and ideas come from our impressions of the world, derived through our senses.