A new quality or attribute that is not present in the constituent parts, an attribute that forms or emerges when a set of parts come together in a working relationship, eg, microchips/electronic activity/computer information processing, internal combustion engine/ motion, brain architecture/electrochemical activity/consciousness, etc.
Many of us think such is just the appearance of something not defined yet as the result of inadequate analysis. Many of us of who think this way believe things work as described by thermodynamics. Things aren't created. Things are realized from combination within the parameters included in the combination. Emergence is being supported mainly by those who don't cotton to reductionism.
Togo this also explains why I don't think it really make sense to look at at decision behaviors without understanding underpinnings.
Yes, because you have a preference for lower levels of explanation. Reductionism is a description of what you're doing, but not a reason. So, the same question to you as to Gazzaniga's remarkably convenient ET. Why only at that level, and no other?
Let's the flip the question around. Does it make sense to look at the underpinnings without understanding the overall process? If not, why not?