There is an intriguing quote from Pirsig's SODV (Subjects, Objects, Data, and Values) paper where he mentions our traditional five senses along with our sense of value, and then states baldly that "Values are phenomena".
The Metaphysics of Quality follows the empirical tradition here in saying that the senses are the starting point of reality, but -- all importantly -- it includes a sense of value. Values are phenomena. To ignore them is to misread the world. It says this sense of value, of liking or disliking, is a primary sense that is a kind of gatekeeper for everything else an infant learns.
What exactly does Pirsig mean by phenomena? Is value a phenomenon similar in some ways to light and sound?

Since Pirsig makes the broader claim that all reality is value, some have criticised this passage as making a claim that our sense of value is a separate sixth sense, when in fact it must encapsulate the other five - unless, of course, some distinction between two uses of 'value' is being made. Indeed, this is the case. The traditional senses, and the things they sense, are static value. The 'sense of value' in the SODV paper, however, refers to the direct sensing of DQ (Dynamic Quality). Since the paper was intended for a general audience, Pirsig probably avoided the technical phrase 'Dynamic Quality' and opted for the more familiar term 'value'. But this is what he means.

Pirsig does believe that the sense of value is akin to the five traditional senses, but he is clueless, indeed speechless, about what mechanisms in nature and in particular, the human body, might pull this off. For lack of evidence he must rely on the credibility of a mystic realm that can make all this happen as if by magic.

But let's look elsewhere for textual support. In Lila (p. 88, Bantam paperback), the author speaks to Rigel over breakfast...

Quality, on which there is complete agreement, is a universal source of things. The objects about which people disagree are merely transitory.

My oh my, what smart talk, Richard Rigel thought. "What 'universal source of things'? Some of us can do without that universal source of things, that no one else seems to talk about but you. Some of us would rather stick with our good old-fashioned transitory objects. By the way, how do you keep in touch with that marvelous 'universal source of all things'? Do you have some sort of special radio set? Hmmmm? How do you keep in touch?"

The author did not answer.

"I'm waiting to hear," Richard Rigel said. "How do you keep in touch with Quality?"

The author still didn't answer.

"Let me ask an easier question then," Richard Rigel said. "You are in contact with this 'universal source of things', aren't you?"

"Yes," said the author. "You are too, if only you'd understand it."
Whereas Pirsig bristles at Rigel's assertion that Quality is his God later on in this passage, he remains conspiculously silent when asked how he tunes into this universal source of things, and yet he affirms that he is in contact with it. In Lila's Child I was surprised to read that Pirsig intended Rigel's attacks to be the best arguments against the MOQ (Metaphysics of Quality) he could conceive, a far cry from the foil I had always thought Rigel to be. DQ is posited by the MOQ to be 'out there', and not a thing that is manufactured by the brain. In Lila, Pirsig says how for years scientists have been trying to find the area in the brain where value is located, and have come up empty.

But in a letter to Bodvar Skutvik (15 Sept 2000), Pirsig seems to have a change of heart when he writes:

I had always assumed that this blockage of direct quality perception was social, but in Mexico a few years ago I talked to a neurologist who argued that it was physiological. She said that recent experiments are showing that the right side of the brain, the "artistic" side, filters all experience before it reaches the left "rational" side of the brain. This would concur with the MOQ assertion that value precedes concepts in human understanding. I have read elsewhere that the left rational side of the brain can never perceive the right brain as an object, but only receive messages from it. This would explain why everyone knows that something is better than other things but no one can define what this betterness is. All they get are the quality messages but they don't know where the quality messages are coming from.
Since it would seem that neurophysiology explains why values precede intellectualizing, and why it can't be defined, you would think that he might be convinced that values originate in the brain afterall. But he isn't. He saves his old beliefs by concluding: "This is not to say that the right brain creates the quality, only that it filters it before passing it along to the left brain for conceptualizing."

Perhaps emotions, which are also pre-intellectual, are the source of value, and we've been confusing DQ with biology all along. No. Pirsig says "the MOQ would classify emotions as mere biological responses to value, not value itself." It seems the universal source of things is always one step removed from something we can know about.

Pirsig thinks that many people are 'quality blind', and as a consequence they cannot understand or accept the MOQ. Such people might understand quality judgements, for example, but not Quality itself. Much of the cause of this "is persistence of the materialistic, objective, historic tradition that hopefully will be overcome in time." Yet ironically, Pirsig thinks that good old-fashioned "objective" evidence will advance the MOQ faster than anything else.

And what might that evidence be like? Let's have some fun. Note that light lets in through the body at the eyes and its sockets and gets processed by the brain. Sound lets in through a hole in the ears and makes its way to the brain. Smell lets in through holes in the nose and also winds up in the brain. Taste lets in through another hole in the head (the mouth) and makes its way to the brain. If DQ is analogous to these senses, it too would enter a body orifice and find its way to the brain. Perhaps some future scientist will discover an almost indetectable ray, dub it q-ray, determine that it enters the posterior, impinges on the base of the spinal column and shoots upward along it to the right brain. This theory would have the advantage that it explains the tingly sensation along the spine during the more awesome Quality Experiences. (Kundalini, anyone?) Plus it would explain the cultural titles "anal" and "tight-assed" attributed to people having a Quality blockage.

I've occasionally wondered what private ruminations Pirsig has entertained about the mechanisms for sensing DQ, but I imagine none of them, especially the one presented here, are worthy of public discourse!

Glenn's Postmortem MOQ Page