If we were all suffering from a neurological condition affecting the left side of our brain and our perception is dominated by its sense of reality how would we know?

Has one side of our brain been damaged? Is this the side that defines our reality and tells us we are OK?  This is the question Tony Wright asks.
Here’s the basic plot,
It is accepted that the left side of our brain plays the dominant role in providing us with our sense of who we are and how we perceive the world.
It is accepted that the left side of the brain is deficient in a number of basic functions, it does not perceive reality rather it invents an approximation (it is permanently deluded). It has no ability to understand context, so for example the left side of the brain (we, me, I) will find it very difficult to see how the pieces of information on this website relate to each other.
The left side of the brain may appear understand the concept of its limited function yet be unable to update its reality and respond appropriately.
It is presumed that this situation must be advantageous and be the product of some kind of evolutionary process.
It might be worth asking whether the dominant side of our brain made this presumption and whether such a presumption is in any way suspect?
Is it conceivable that there could be an alternative explanation literally staring us in the face!
Before jumping to any conclusions try making sense of the following.
This link provides an overview of the left brains delusion in regard to and as part of its dysfunction.  If we were all suffering from a neurological condition affecting the left side of our brain and our perception is dominated by its sense of reality how would we know???
http://www.psychlaws.org/BriefingPapers/BP14.htm
Some more examples of what happens when the left side of the brain is ‘left in charge’
http://psych.utoronto.ca/~peterson/psy430s2001/Ramachandran%20VS%20Evolution%20of%20self-deception%20Med%20Hypoth%201996.pdf

This research suggests the theory that the specialist skills ascribed to the left hemisphere are not selected adaptations as generally presumed.
http://focus.hms.harvard.edu/2005/Jun10_2005/neuroscience.shtml

Definition of Anosognosia, is this the term that best describes the human condition?
http://encyclopedia.thefreedictionary.com/anosognosia