Scientist never doubts there are reasons the world behave as it does- the search for such reasons is the essence of scientific Discovery.
Realists believe that scientific statements, serving that purpose, are the truth statements about reality, a kind of orthodox stance. They deny experimental measumenrs are theory-ladden.
But others take scientific claims in a lighter light. They see inherent beliefs as weaknesses in the scientific Discovery process that intrrfere in our true realist aspirations. They see experiment al validation as a singly available persuation method for scientific claims and not as the unshaken reality test it is perceive or they keep the benefit of the doubt for such unconsciously twisted attitudutinal reasons as that
because we are material things that are criteria for reality are on its capacity to bring material changed (anthropocentric bias).