Protagoras visits the Darwinian planet.

Humans create their own reality Humans are the masters of the world. This, in a nutshell, is the message of the great anti-Socratic philosopher, Protagoras.

The underlying question here is whether humans invent reality or discover it. invent it, every bit, says Protagoras. This is a stupendous insight into the fact that the cultural world we inhabit is our own creation. Our minds have made all these wondrous things. We bring culture into being: art, religion, politics, ethics, philosophy -- even science. Angels and gods and monitored elections, spears and railroads and computers -- we invented them all.

But do we invent every single thing? Even the natural world, the physical world which upholds us and the biological world out of which we have sprung? We invent the strings with which we play upon the world as if upon an instrument -- including the notion of a world and all the philosophies which flow from the realization of being in a world. But the world itself we do not invent.

Protagoras says there is no "world itself." There is only the world as it appears to me. Protagoras, meet Charles Darwin.

We who are cultural relativists do indeed lay wreaths at Protagoras' feet. it seems pretty clear -- at least to humanists -- that all the cultural splendors we boast, in all their beauty and complexity, have been brought upon the scene from nothingness or from blank apedom by our own sapient selves.

What I want to argue is that there is something we didn't invent. If Protagoras could just look around this planet for a second with the eyes of a Darwinian, he might realize what was missing from his vision.

The other night I tripped on a step and fell on a concrete sidewalk. Nothing about this was invented by me, other than the sentence which just now describes it. I did not invent the flesh, bone, concrete, or gravity which came into play in forming what I call my experience -- though the words, I grant, came from my society. Neither did I invent the physical brain which experienced the event and conceived the above description, though I grant that the notion of brain and such is the invention of my society. Put another way: the sidewalk took my measure.

Pause now to consider what we have learned from the Darwinian revolution. It has great bearing on the problem of knowledge (which Protagoras himself introduced into the history of philosophy) -- and about how any measure of reality can be taken at all.

The first thing to notice is that humans, with all their wild, creative minds, have evolved out of a primitive physical pot of animal flesh. In this seething, swarming pool of genes, natural selection saw to it that what worked got passed along and what didn't was not.

Mind in animals was part of what was working (for many sound survivalist reasons). Any aspect of animal mind that didn't "correspond" in a sufficiently realistic way to what was "out there" didn't get passed along and, therefore, isn't with us today. Primates who "invented" grapevines to swing on perished long ago. Surviving primates and their descendants "discovered" where the real grapevines actually hung. Some opinions about grapevines were just downright better than others. All of our own ancestors had good opinions about grapevines, and so do we, generally speaking (especially the winemakers).

Each person is not the measure of all things when it comes to the preexisting natural world out of which we evolved. Opinions that are radically out of touch with biological conditions fade away. Vine tenders who mismeasure grapevines end up as dock hands. (This is not to deny that what 'seems so' to the inept vine tender really does "seem so" to him or her.)

Protagoras lived among us for awhile because his mind was, in most important respects, attuned realistically to what was actually the case in the world of his time. In the words of the song "The Gambler": he knew when to hold 'em, knew when to fold 'em, knew when to walk away, and knew when to run. Otherwise we would never have heard of him.

Picture yourself as one of our ancestors leaping out into the void for a swinging vine. If you invent a vine that is not really there, then you are not our ancestor and we are not your descendants. Welcome to Darwinian epistemology.

This simple example is actually the answer to the basic conundrums of modem philosophy. Remember when you were a sophomore how you reveled in being able to show that no one could prove that yonder table existed? The flaw in the tradition of epistemological puzzlement is that, except for Aristotle, no philosopher prior to 1859 had dealt with biology or evolution.

Your brain is attuned to a reality out there. If this were not so, you would not now exist to be arguing about it. Correspondence between your brain and a reality "out there" has all been taken care of in your animal and primate lineage, which over the ages has adapted itself to reality -- or perished. Rest assured, your brain is a good tool for scooping up reality. The brain evolved with reality -- otherwise it did not evolve at all.

What's missing in Protagoras -- and in all philosophy prior to the Darwinian watershed -- is biology. Protagoras and his avatars have no sense of how our minds are enmeshed in a tangled web of physical evolutionary history. Simply put, the world was here before we were. it made us, we did not make it.

I got into an argument the other day with some friends of mine about cats and animal rights. I found myself saying that humans are kings here, the masters. We make the rules and we can, by damn, make whatever rules we want. If I want to impound a cat, drown a cat, or eat a cat, I can do so without violating any ethical norm known to me -- save only that I not be cruel. I do the measuring of cats.

It was pretty much a Protagorean position. We are the measure of all things. We can do what we want here -- not because some god has given us dominion over things but simply because we are stronger and the noetic sphere is ours. We decide what is good for ourselves and we decide what is good for cats -- as far as concerns us. If in cat-world they have a different opinion, that's their worry.

But when I sat down to explain about kings and rules, I ground to a halt. First, I couldn't describe any real sense in which we were "kings" on Earth. Second, I couldn't figure out what "rules" we had made other than the cultural rules governing our own societies.

I want you to understand what I'm trying to say. I happen to think humans are the most glorious things going. Not that we are in any cosmic sense "highest" -- Darwin forbids that thought. Just that we're on top and making out like gangsters. In spite of all our shortcomings -- especially the ethical ones, the brutal and despicable ones -- there's nothing better than us around right now. I glory in the great things we do. Our inventions especially -- yes, Protagoras, especially these. I love every wild and crazy thing we've invented: skateboards, moon shots, neon signs, blue jeans, computers, music -- whatever. For all these things I crown us kings.

But this is a ragged notion. Doing all these glorious acrobatics does not make us kings of anything. It certainly doesn't make us kings, in any sense, over the rest of the biological world.

Here is where we need some biological breadth. Many species do marvelous things, unimaginable things, smart things, strong things, beautiful things. Calling ourselves kings over other life forms is the very opposite of the cultural relativism we, as Protagorean humanists, so proudly proclaim. It's a contradiction: rash, unfounded, boastful, and quite blind.

In truth, we are not kings over anything. How poorly do we govern even ourselves! A toast to the short experiment we call democracy, to a few benevolent leaders. Meanwhile, alas for vast portions of the human world still bound by tyranny and slavery, poverty and torture. Alas for the many ills caused by human kingship.

But we're not quite to the main point yet. That comes with the question of rules and who makes them. Do humans make the rules on this planet? What rules are we talking about?

My essay on cats got snarled when I started thinking about the laws of physics and chemistry and what might be called laws in biology. I couldn't see humans having a hand in any of them. We didn't become lawmakers until we got to things like incest, red lights, and tax exemptions. Human laws concern only human social institutions -- the froth on the top of the wave of life. We don't make the rules of the physical or chemical worlds. These rule us. Ditto in the biological world, the level at which we live and breathe and have our being. We have no say in it.

Take, for example, medicine and all its inventive, manipulative wonders. We transplant kidneys and make artificial hearts. It looks like we're imposing our rule upon nature but actually we're not. Researchers toil to discover the deep and hidden rules of nature. They learn how to work within these rules. Only a profound and detailed knowledge of how human biology "really works" enables us to transplant kidneys. Nothing good happens in medicine without an understanding of how things "really are." Let Protagoras measure kidneys any way he wants -- and hope he never needs one. Meanwhile, medicine advances as biology dictates, minus the musings of Protagoras.

Beyond the obvious biological facts -- such as the fact that red blood cells transport oxygen -- there are biological realities which reach right up into our social lives, our mental and cultural lives. Biology affects even our culture, so say the sociobiologists. This is because we are social primates descended from certain definite other social primates. Much of our behavior comes from these dim biological depths. We do what we do, in part, because we are animals of this particular sort. Other animals do otherwise.

I had to conclude from these considerations that, far from being rule makers, we look more like rule breakers. We're not always good at going with nature's flow. Homo sapiens seems both able and willing to buck the rules that nature has been laying down for eons. Not infrequently these are rules of life and death.

Consider another example. it is one of the many small rules of nature that the floodplain of a river is a place where many things are achieved: flooding is slowed and ameliorated, underground aquifers are replenished, chemicals are reprocessed, waste products are recycled, aquatic life is given a nursery, and plants and animals of certain kinds are supplied their unique habitat. This arrangement was working long before the appearance of humans. It was a reality awaiting our discovery.

Humans, however, are powerful -- if not law-abiding. We come to a floodplain and do what we want. We build roads, bridges, dikes, farms, car dealerships, condominiums. But think about it: are we making or breaking rules of nature?

Humans haven't made a single rule regarding nature, but we've broken plenty. Competent as we are, there's much we can do. But we can't make the rules of biology. All we can do, it seems, is break them.

All this is not to say that nature provides a norm for ethics or that is determines ought. Neither is there any comfort here for what Catholic theology calls "natural law." No, ethics is one of our artifacts. The facts of biology, on the other hand, represent discovery.

Protagoras responds, "You say these things, but others say other things." That's fine, Protagoras. You and the others say other things until you perish. Biology will take care of you. it will have the last word.

But this discussion should not end as a Humpty Dumpty power struggle. There's a philosophical point to be made. Why can't we say that discovery is one of our powers, just as invention is?

Protagoras abruptly declares that invention is all and rests his case. May we not declare, with greater reason, that discovery is also a part of things? What we discover is that discovery itself is a window to reality. We discover biology and, with it, the limits of Protagorean thinking.

The key to this reality is not any philosophical system or fancy argument. In fact, it lies outside philosophy altogether. The key is biology -- in its contemporary, Darwinian version. Philosophy has always lacked this essential understanding of our condition, and for this reason has always been lame.

Dear Protagoras! You are great in helping us understand the works of our human days and hands. You got it right: humans are the measure of all things human. But (let us help you a bit) certain things preceded humanity which humanity does not and cannot measure. Though understanding and formulating of such things is a certain kind of human measurement -- prone to error as are all human measurements -- don't let this deceive you. You, the measurer, are embedded in a biological matrix over which you have no control and no command. It is not yours to criticize or construct. It made you a measurer in the first place, and it measures you now. Step outside its boundaries as you please, but know that you will pay the consequences. You are not king and you do not make the rules.

About cats. Along with all the other living forms with which we are embedded in the web of life, cats have exactly as much value as we care to bestow on them. Same as anything else. Cat, butterfly, snail darter, fetus, felon -- their fates are in our hands. As good Protagoreans, we measure them.

And yet our well-being, our very existence, depends on the web of life in ways we only dimly understand even as we measure it. If we mismeasure this web, break its rules, and destroy it, we perish with it.

In the Protagorean world, there is no such thing as "mismeasurement." But that is a mistake. We have arrived at the conclusion that, if we wish to live and live well, we must bring our measurements into harmony with the measurements already existing out there in the real biological world. We evolved doing this. Let's keep doing it.

This description puts humans in their place in nature yet leaves all values still ultimately relative. Values are relative to humans. Indeed, even human life and well-being are not absolute values. What is valuable to us is not thereby valuable in itself. Nature is not here to serve us. Neither is nature here to serve even life in general, for planet Earth does not care whether or not it supports life. Ultimately, the sun will grow big and red, and life here will fail.

Meanwhile, humans enjoy a space of time during which they will be the measure of all things human -- and the rest of nature will be the measure of humanity.