The technical definition for reality in philosophy is:
existing objectively; actual (not merely possible or ideal), or essential, absolute, ultimate (not relative, derivative, etc.)
http://www.yourdictionary.com/real
Existing objectively in the world regardless of subjectivity or conventions of thought or language.
So the main conditions which define what realism are is that it must be objective and independent of oneself. It presupposes a world made out of many human observers looking on at a world populated by many objects that can be acted upon and examined by the human observer.
The philosophy of idealism says that all objects are just sensory constructions/linguistic constructions/mental constructions within the observer itself, hence it is impossible that any objects are existing outside of us which are independent of us or that you can examine and act upon them without actually affecting them.
Edmund Husserl called the notion of reality to be a "natural assumption" The natural assumption is the belief that there is a world out there that one can examine and which will yield to our examination. An assumption that all physical scientists make. But the reality is that without consciousness there would be no world in the first place. Hence, the world has a contingent existence depending on consciousness: it is therefore not real. Husserl's project was to find out what the structures of consciousness are and how they construct reality.
Today in philosophy, many post-modern philosophers posit that reality is just a construction of language. That chairs and tables do not exist for example, because they refer to simply objects humans have identified to be the same object exihibting the same behaviour. Here we make two major assumptions 1) We separate out the chair from everything else around it seeing it a separate object and 2) We assume it is the same object enduring every moment because it seems to exhibits the same behaviour.
People like Asuri hate us philosophers because we philosophers point out the obvious assumptions they swear by. Physical scientists particularly hate postmodern philosophers because postmodern philosophers point out the assumptions they make. But what people like Asuri cannot negate is that these observations are pointed out by some of the greatest philosophers of all time.
The philosophers of the Upanishads first pointed out how everything was just name and form(nama, rupa) That is whatever object we isolate from perception is just a differentiate of a form in our perception based on our linguistic identification of it as as object exhibiting the same behaviour. In the Chandogya Upanishad, when Narada approaches Sanatkumara on how he has knowledge of everything but no contentment, Santakumara answers him, "All you know is name and form" When Narada inquires about anything beyond name and form, Sanatkumara responds, "Speech precedes name and form" This dialogue goes on for a dozen more categories before Brahman is reached as the ultimate reality.
Buddha pointed out that nothing ever endures, that everything is incessant change. The illusion of enduring objects is what causes suffering, for then we cling onto those objects, only to finally realise their transient nature. Buddha also adopted the name and form philosophy of the Upanishads.
Plato also pointed out in his allegory of the caves how taking the world to be real is just an assumption. It could very well be like on the cave walls the dancing of shadows, with an object outside of the world that is casting the shadow.
Bishop George Berkely pointed out in his critique of Descartes dualist philosophy, how the splitting of reality into a subjective and objective component was an assumption, it could just as be possible that the subjective and objective are both within the mind itself and all of reality just a mind-stuff. The notion of there being two separate universal substances is just an assumption.
David Hume pointed out the obvious assumption we make that an object is enduring just because it seems to look the same. He famously asked whether anything continues to exist when we are not looking at it, and how can we be certain it does. Perhaps it momentarily goes out of existence and comes back. Perhaps it goes out of existence and is replaced by something else.
Immanuel Kant pointed out that our obvious assumption of the world being completely objective with us just passive receivers of sense impressions from it is an assumption. Rather, it was clear to Kant that the world was a construction within the mind itself, where sense impressions are received by the noumenal level of reality and then phenomena constructed by the ordering categories of the mind(more or less confirmed by neuroscience today)
Arthur Schopenhauer pointed out how the world was a representation of intentions. Kant's noumenon was actually desire. As long desire as remained, the need for constructing objects remained, and as long as this process continued one was going to suffer because objects are not real.
Quantum physics have proved how matter really is an undifferentiated and inseparable whole, until it is observered and the very act of observation causes this undifferentiated and inseparable whole to seem to be made out of differentiated and separable things in time and space.
People like Asuri hate us because we dare to bring into question the most obvious assumptions they make about reality and successfully show that they are assumptions.
