If an idea requires the correlation of two persons' thought processes to be fully comprehended, is it still an idea, or has it become something else?
If I was born deaf and understood the idea of blue and my born-blind friend was a great music lover who understood the musical meaning of Rhapsody (http://en.wikipedia.org/wiki/Rhapsody_(music)) and thus in conversation we could help each other to approximate an idea of a piece by Gershwin (http://youtu.be/1U40xBSz6Dc), what is the status of our shared ideation?
I know this is rather general and perhaps qualifies really as a question about the nature of all discourse, but I am interested to know what the positions on this are - and in a way I can grasp without many years study.