Certainty, Duality, And Nonsense

We'll never be able to perceive everything. Nor does every sensory perception constitute an exact indication of what reality is actually like. But perception is the only data we have to make our way through life. Anything else is nonsense.

In Alan Greenspan's memoirs, The Age of Turbulence, he recounts a funny story about logical positivism and his time with Ayn Rand. Unfortunately, I lost my copy of this book in an airport years ago, but I managed to find a citation for the story in question in this LRC post by Roderick Long:
After listening for a few evenings, I showed my logical-positivist colors. I don’t recall the topic being discussed, but something prompted me to postulate that there are no moral absolutes.
Ayn Rand pounced. “How can that be?” 
“Because to be truly rational, you can’t hold a conviction without significant empirical evidence,” 
“How can that be?” she asked again. “Don’t you exist?” 
“I … can’t be sure,” I admitted. 
“Would you be willing to say you don’t exist?” 
“I might….” 
“And by the way, who is making that argument?” 
Maybe you had to be there — or, more to the point, maybe you had to be a twenty-six-year-old math junkie — but this exchange really shook me. I saw she was quite effectively demonstrating the self-contradictory nature of my position. … It dawned on me that a lot of what I’d decided was true was probably just plain wrong. Of course, I was too stubborn and embarrassed to concede immediately; instead, I clammed up.
And the punchline of the story:
Rand came away from that evening with a nickname for me. She dubbed me “the Undertaker,” partly because my manner was so serious and partly because I always wore a dark suit and tie. Over the next few weeks, I later learned, she would ask people, “Well, has the Undertaker decided he exists yet?”
While this exchange seems like so much hoity-toity New York high society mumbo-jumbo to some, nearly everyone is familiar with a simpler version of the same problem, accurately conveyed by this item I found on Quora today:
How can you know for sure that your body is real and not just an avatar?Let's assume that our consciousness has no direct contact to the outer world. And that all what we perceive is "just" a our mental model of the world. 
Is there anything at all what can be said then about our real "us"?
We might otherwise call this "The Matrix Problem," or the "How Do We Know It Isn't All A Dream?" problem, or maybe even The Simon Grey Problem. (I kid! I kid!)

Well, I think I've figured out what I don't like about these problems: There is no duality between the opposing viewpoints. Allow me to explain.

What Is Duality?
First let me stipulate that when I refer to "duality," I'm referring to the kind of logical duality that pertains to category theory. It's possible to make this concept extremely formal and complicated, but for my purposes here, it should suffice to say simply: Things can be categorized.

This seems like a banality, but it's important. Without intuitively understanding duality, you wouldn't know where your fingertips end and the rest of the world begins. Infants, for example, are said to have to learn that they are a separate and distinct person from their mother. To an infant mind, because mother and child are often inseparable, it is not immediately obvious that the mother is a unique being, not a part of the child's own consciousness.

So another way of describing this kind of duality is simply to say Things that are different are not the same thing. Again, this sounds obvious, but it's important.

Reality As Reality, Vs. Reality As A Dream
Let's return to that Quora question I linked to above. What is the real problem with describing reality as being nothing more than a dream? The problem is that there is no discernible difference between dream-reality and reality-reality.

How would your life change if you found out that your consciousness is nothing more than a dream being had by a turtle riding in the back of a giant, cosmic, pickup truck, and that the turtle will never wake up until long after the dream ends, and your conscious along with it? The answer is: It wouldn't. Your consciousness is unaffected by the hypothetical prospect that its nature is fundamentally different than it seems in a mystical, magical way that you will never be able to detect.

For you, the existence a magic turtle does not fundamentally alter anything about your actual consciousness. Thus, there is no essential, defining, important difference between dream-reality and reality-reality. It's all just reality, regardless of which homunculus is the true entity experiencing it. It's the hand you actually perceive that feels heat when you hold it near a flame; whether that perceived hand is just a turtle's dream is irrelevant to you, and always will be, so long as that dream is defined to be something you will never be able to verify or falsify.

In other words, there is no meaningful duality between the two concepts. In short, the question posed at Quora is nonsense.

How do we know whether we are experiencing X or Y, where X is defined to be everything that we perceive, and Y is defined to be everything we perceive, plus any number of things that will never, ever be perceived by anyone, anywhere? This question cannot be answered be we cannot differentiate between X and Y. X and Y are exactly the same state of affairs. There is no duality between X and Y, only unity.

Faith, Knowledge, And So On
Here's an even less abstract example: Christians believe in the Holy Trinity. In very crude terms, the Trinity consists of god, who can do whatever he wants to do; Jesus, who is god in the physical flesh; and the holy spirit, which is basically all the heebie-jeebies that we get that make us insist that we have proof of the supernatural. So the question is this: What is the difference between a trinity of characters who make up an all-powerful god on the one hand, and just an all-powerful god on the other hand?

The answer is: nothing. There is no difference between an omnipotent god and an omnipotent god that assumes various names and shapes. Part of being omnipotent is having the power to - among other things - assume any name and shape one pleases. Thus the ability to assume names and shapes confers no additional power that omnipotence didn't already afford.

The Holy Trinity is exactly as meaningless as saying, "Kobe Bryant is a major league professional basketball player who is also a member of an NBA team." Any statement that confers no new information is meaningless, at least insofar as duality is concerned.

And, in fact, the existence of god is precisely the same phenomenon. The physical universe is the sum total of all perceptible time, space, matter, and energy. God's universe is the physical universe as I have just described it, plus a bunch of stuff that will never, ever be perceived by anyone, anywhere, at any point within the physical universe.

As such, "god" is a magic, sleeping turtle in the back of a pickup truck. Including "god" in any description of reality conveys exactly as much additional information as stipulating that Kobe Bryant is both a major league professional basketball player and a member of an NBA team. There is no duality between a universe that was created by a god and one that was not created by a god. There is just "the universe." There is no point adding extra, invisible features that can't be perceived. By definition, they are not part of the universe, so what are they doing in a conversation about the universe?

It's interesting to note the parity between those who deny reality, like young Alan Greenspan, and those for whom reality isn't enough, who must add a wide array of imaginary things to reality that cannot be perceived. It is fascinating that while the former category of people seem to think they are being skeptical of something, the latter category think they are asserting a belief. In both cases, though, the claim amounts to absolutely nothing.

It's important to keep this in mind when people assert either that our perceptions are unreliable indicators of reality or that reality consists of a great many imperceptible things. It's not that either of these is an objectively false claim, it is simply that our understanding of reality is completely unaffected by the truth or falsehood of either.

We will never be able to perceive every aspect of reality. Nor is every perception we have an accurate depiction of reality (think about phantom pains, for example). But the key point here is that data matter. Perceptions genuinely inform our understanding of reality; that which can never be perceived, simply does not.

Understanding this concept is the key to keeping things straight when it comes to science, philosophy, and indeed your immortal soul (cue spooky music). 

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