Implicit beliefs are assumptions. To assume is not the same thing as believing something is the case. To assume is to take for granted. When I walk, I assume my feet will encounter resistance. When I cook dinner, I assume hubby’s coming home. I’m not sure we can talk about assumptions as discrete cognitive objects the way we speak of beliefs.  Assumptions are not the product of reflection. People may “come to believe”, but they don’t “come to assume”. Assumptions are more like default settings that persist because they have been unchallenged and lead to good-enough outcomes (like reaching the mail box or having a nice dinner). Assumptions don’t require that we entertain the possibility of their being wrong. If we do entertain that possibility but conclude the assumption is valid, then what had been an assumption becomes a belief.