A parable to illustrate the limits and progress of science and human knowledge.
There is a community of intelligent beings who live in a place they call Cognita. It's made up of two islands: Prima and Segunda. Collectively, they call themselves the Cognitians. Their world is composed of a variety of natural environments, full of life in a multitude of forms. All the life on the two islands (and the waters surrounding them) evolved from a single common ancestor. The Cognitians themselves descended from a single ancestor (the Proto-Cognitian) who was herself born of an earlier species of beings (the Pre-Proto-Cognitians or Precognitians). All Cognitians were born on either Prima or Segunda and none has ever ventured beyond them.
The Precognitians and Cognitians had intellectual skills far beyond their ancestors and the other animals with whom they share their world. Whereas other species use their teeth, their size, their claws, or their eyes to get by, the Cognitians and Precognitians use their brains. The Precognitians were similar to the Cognitians in many respects. They used tools like the Cognitians and could communicate and use symbols in the same way as the Cognitians. The Precognitians made a major intellectual leap that set them apart from their own ancestors (the Pre-Precognitians) and that they passed on to their Cognitian descendants. They discovered that they didn't know things. Before that realization, no one had ever seen the world as consisting of things that are known and things that are unknown. They experienced things as they lived and learned lessons as they went, but they never considered the unknown in the abstract. That Precognitian invented the idea of ignorance and it's first application: the question.
Ideas are tools. They are employed, like all tools, to further some end. Awareness of one's ignorance is not necessary for learning, Neither is asking a question. One simply needs to experience something, remember it later, and apply the memory to a subsequent situation. Learning is a trait that came about long before the earliest Precognitians. But understanding that you don't know something specific is a different thing.
Knowing that you don't know everything allows you to ask a question. It is a fundamental precursor to experimentation and as such, the granddaddy of science.
After acquiring these intellectual tools, the Precognitians and the Cognitians embarked upon a great intellectual journey. They developed a written language and were able to record their ideas and experiences for future reference. They began to describe the world around them in earnest. The sky, the waters around their islands, the earth beneath them were all examined in entirely new ways. These observations were built upon by each successive generation of Cognitian scientists.
Despite all of this, no Cognitian had ever explored beyond their horizon. They had never gone beyond their two islands. One could draw a circle around their two islands and see every thing inside that circle as known and everything outside it as unknown. That circle represented the literal and figurative limit to the Cognitian's knowledge. The majority of Cognitians would say: "There are only two islands on Cognita." This was because it was the position best supported by the evidence.
One day, a Cognitian named Optica, building on the work of many Cognitians who had come before her, put together the first telescope. She pointed it out at the horizon, and there, she became the first Cognitian to see what would come to be known as Tercio, the third known island of Cognita. She recorded her observations and publicly distributed them.
In this small act, she expanded the circle of Cognitian knowledge dramatically. She changed the way that Cognitians, both scientists and laypeople, looked at their world. Not only did she change the way they thought of the geography of Cognita, she reminded everyone that they must always be willing to change their mind in the face of new information.
Before her discovery, there had been a debate between Cognitians who said that there were other islands in their world and those that said there weren't.
Both sides had evidence to support their positions. The "other-island" camp argued that we already know that there is more than one island on Cognita. The "Only two" camp argued that Cognitians have recorded their observations of Cognita for a very long time, and only observed two islands. In other words, evidence of the two islands were part of the Cognitian circle of knowledge and direct evidence of any other island was not.
The evidence weighed in favor of the "only two" theorists. They had the stronger position based on the available evidence. Optica's discovery changed everything. Now, the "only two" position was rendered completely untenable.
This debate was about whether or not there were other islands, but there was another debate about whether or not there might be other islands. Almost all Cognitians had agreed that there might be other islands, just that there was insufficient evidence to affirmatively declare their existence. Optica radically changed this debate as well. Now that a whole new, previously-unknown island had been discovered, the argument that there might be others was dramatically strengthened.
This is like the debate about extra-terrestrial intelligence and alien contacts with Earth. Like the first debate above, some hold the position "aliens have visited Earth" while others hold the contrary view. Today, the later is the best supported position. Ironically, this is largely the premodern view. As evidence of the scale and age of the universe grew, the position that we were alone in the universe weakened. This culminated during the heady, more optimistic days of the post-war era. The great Carl Sagan advanced the "We are not alone" position. He did so primarily by re-evaluating existing analyses. It was not until a more recent re-evaluation by Peter Ward and Donald Brownlee and new evidence, including the observations of Shoemaker-Levy, as it smashed into Jupiter, that the balance shifted back to the No view. Observations of Shoemaker-Levy 9 supported the idea that gas giants in the right place are a prerequisite to intelligent life arising on a planet and that therefore, there are less planets overall where it could arise (although it should be noted that there is counter-position to this idea as well).
Back on Cognita, Optica didn't rest on her laurels. She pointed her telescope at the night sky. Instead of new Islands, she discovered whole new types of things. When she looked at familiar points of light in the sky with her new telescope, she saw little white smudges, like tiny clouds. She discovered nebulae. She also saw that whereever she looked, there were many more stars than could be seen with the naked eye. She also saw that one class of stars that the Cognitians had called Planets, because of the way they moved relative to the other stars, were disks, not points.
Now, we are no longer talking about a "circle" of knowledge, but a "sphere." Cognitians now saw their sky not as a two-dimensional projection rotating above them, but as a three-dimensional area with depth, which contained objects both distant and near.
On Earth, as on Cognita, Every piece of evidence, collected and analyzed, and the hypotheses they support or weaken push that Sphere of Knowledge further out. There is a figurative sphere, a spatial sphere and a temporal sphere. Presently, we have evidence of events that occurred approximately 14 billion years ago. That is the edge of the sphere. Beyond that lies the unknown. Consider how much smaller the sphere was, when the collective knowledge of humanity had little or no understanding of the world before the earliest oral histories.
The sphere extends forward in time as well--with a significant caveat. The present is causally related to the past and the future. But there is a significant difference between past states and future states. Past states have actually been, whereas future states may or may not come to be. We know that the universe existed in the past, we do not know that it will continue to exist in the future. Even if all evidence points to a particular conclusion about a particular point in the future, we must always concede that at any point after the present, things may be different in a way that could not be anticipated by observations in the present or understanding of the past.
The temporal sphere of knowledge must be divided into hemispheres--one for knowledge of the past and one for knowledge or the future. Both are real and both are subject to change. But the later must carry with it an asterisk reading: "past performance is no guarantee of future results."
The sphere of knowledge will always be limited. It will always be finite. It will always be subject to change. These, in no way, undermine the incredible expansion of the sphere that we have seen and the confidence we should have in relying upon it. It has seen great leaps, and also ebbs. But we deserve credit for how we, as a species and as individuals, have contributed to it.
Our ability to reason is without parallel in our world. Your mind is your most powerful tool and your best hope in life. Use it. Celebrate it.
Comments to Joe Hubris.