Hypothetical realism
Hypothetical realism describes the epistemological assumption that there is a reality which is shared by humans (or a wider group of ethical subjects). The concept of hypothetical realism is due to Gerhard Vollmer.
Philosophical Remarks
The assumption of realism tends to appear so obvious to some that even stating it is pointless, and yet it is highly controversial and contentious in philosophy. One root of this contention comes from the fact (or experience) that sensory perception can be deceptive. As a result, it is rather uncontroversial that the state of reality may differ from the mental model which a subject (a human being or other ethical subject) has of reality. It is possible to develop mental models of objects that do not exist in reality, and sensory perception can mislead a subject to presume existence of a non-existent object. This leads to scepticism, and taken to the extreme, this scepticism leads to the assumption that nothing "really" exists and that there is no reality. Such positions are known as "anti-realism" or "constructivism".
It is interesting to note that such anti-realist or constructivist ideas are not consistent with the assumption that there are multiple subjects who communicate, usually humans forming a society and holding discourse. Communication, by all accounts, is transmission of information. It is plausible to assume (e.g. based on experience) that elements of a subject's mental model are different with respect to the difficulty ofcommunicating them. From this perspective, reality can be defined to be comprised of all information that is communicable. This is (possibly) not a precise definition of reality as information that is un-realistic but communicable may exist. It does, however, show that communication is subject to contstraints imposed by an "outside world" which cannot be arbitrarily "constructed" by communicating subjects, and which therefore quite reasonably can be called objective reality.
From this perspective, all mental models of the state of reality are hypotheses, but the assumption that there is an objective reality follows from the assumption that communication exists, and is thus not a hypothesis itself.