What is real? This is one of the toughest questions. Ordinarily we don't pay much attention to it. We just go on with our lives.
But sometimes it's necessary to ponder whether something is really there -- a human-like shadowy shape moving in the woods as we take an evening walk, say (if a serial killer is on the loose, we'll be seriously motivated to ponder that question).
Philosophers are interested in this issue for other less concrete reasons. They wonder about topics such as "Realism and Truth," the title of a chapter in Philosophy in the Flesh, a thick meaty tofuy book that I'm slowly making my way through and have blogged about before here and here.
The authors, George Lakoff and Mark Johnson, do a good job of summarizing the basic problem of "what is real?" and their persuasive solution.
Common sense argues that the world is known directly. I see and feel my laptop. If my wife walked over to the kitchen counter where I'm typing away, she'd see my computer in the same way. Silver and black. Thirteen inch screen. And so on.
The ancient Greeks, along with most non-philosophically and non-scientifically minded people nowadays, had a simple explanation for this congruence.
For them, knowledge that worked was knowledge of Being. Aristotle, for example, saw an identity between ideas in the mind and the essences of things in the world. That identity answered the problem of knowledge. Aristotle concluded that we could know because our minds could directly grasp the essences of things in the world.
This was ultimate metaphysical realism. There was no split between ontology (what there is) and epistemology (what you could know), because the mind was in direct touch with the world.
However, we now understand that this isn't true.
For example, science tells us that objectively there is no green in grass, or blue in the sky. Colors are a product of how the human eye and brain processes electromagnetic radiation of a certain wavelength.
Yet in the morning I'll look out a window and see our green lawn. And I might even see blue sky, though during January in western Oregon, gray clouds are a lot more likely.
So what is real? My subjective direct perception of green grass, the objective scientific knowledge of how light works, or an understanding of how the brain converts colorless photons into greenness through unconscious cognitive processes?
Comments and posts on this blog often touch on this question, albeit usually not explicitly.
I remember a recent exchange where someone argued that to him, his only genuine reality was what he could experience directly. I replied that my direct experience is of the sun rising and setting, whereas actually this effect is produced by the rotating earth. Thus scientific understanding enlarges and affects my understanding of certain direct perceptions.
Lakoff and Johnson take an "all of the above" approach to reality. It isn't possible to settle on a fixed notion of truth, because such doesn't exist.
In much of the Western philosophical tradition, truth is taken to be absolute and scientific truth claims take priority over nonscientific truth claims. We know from the neurophysiology of color vision that colors do not inhere in objects themselves. They are created by our color cones and neural circuitry together with the wavelength reflectances of objects and local light conditions.
...Here is the dilemma: A scientific truth claim based on knowledge about the neural level is contradicting a truth claim at the phenomenological level. The dilemma arises because the philosophical theory of truth as correspondence [between symbols and the world] does not distinguish such levels and assumes that all truths can be stated at once from a neutral perspective. Yet there are distinct "truths" at different levels; and there is no perspective that is neutral between these levels.
In other words, I can truly say "the grass is green" while also recognizing the truth of how neuroscience understands color vision in humans.
These separate truths aren't going to combine into a mega-truth. The way I subjectively see the world is always going to be different from what science tells me about photons and neurological goings-on.
Yet because we humans are embodied beings, the way other people perceive reality is going to be pretty much like how I do -- assuming our brains and other bodily functions are in decent working order. (Someone colorblind, of course, won't see grass the same way I do.)
In the end, whatever works is the only viable criterion for truth, according to Lakoff and Johnson.
We need to recognize that it isn't possible to know things as they are, separate and distinct from human cognition. All we can do is honor different valid ways of knowing. An audiologist can shed tears at the beauty of a Beethoven symphony while understanding how what is heard are "merely" sound waves of various frequencies propagating through the concert hall.
So religion's quest for a detached, objective Perfect Truth is a fool's errand. Forget about it.
In sum, embodied truth requires us to give up the illusion that there exists a unique correct description of any situation. Because of the multiple levels of our embodiment, there is no one level at which one can express all the truths we can know about a given subject matter.
But even if there is no one correct description, there can still be many correct descriptions, depending on our embodied understandings at different levels or from different perspectives.
Each different understanding of a situation provides a commitment to what is real about that situation. Each such reality commitment is a version of a commitment to truth.
What we mean by "real" is what we need to posit conceptually in order to be realistic, that is, in order to function successfully to survive, to achieve ends, and to arrive at workable understandings of the situations we are in.