I just had an exchange with Ian Bogost over on Twitter, after I posted the above photograph of me, Marshall McLuhan, and Eric McLuhan, taken at the "Tetrad Conference" I organized at Fairleigh Dickinson University in March 1978.
Ian aptly said that I needed a "4th" (the "tetrad" has four components).
I replied that the 4th person pertaining to the photograph was the photographer*, which has flipped into the selfie.
Here, then, is a full tetrad on the photograph, and it's flipping into the selfie:
The photograph enhances capture of literal images.
The photograph obsolesces portrait painting.
The photograph retrieves memory, looking at images in pools of water, etc.
And the photograph flips into the selfie.
And it's a physical flip of the camera in the phone, as well as a philosophic flip.
*photographer was my student, Mary Lou Bale
For more on the tetrad ...
the spoken word
McLuhan and the Kindle | McLuhan and the Selfie