“It seems to me what is called for is an exquisite balance between two conflicting needs: the most skeptical scrutiny of all hypotheses that are served up to us and at the same time a great openness to new ideas. Obviously those two modes of thought are in some tension. But if you are able to exercise only one of these modes, whichever one it is, you’re in deep trouble.” – Carl Sagan
What is critical thinking?
I like the definition that critical thinking is, “disciplined thinking that is clear, rational, open-minded, and informed by evidence.” What does this mean? Let’s break it down into pieces.
First, to be disciplined in our thinking means that we do not allow our speculation to wander around, we think about a topic in a systematic way. Second, rational thinking is when we allow logic and the facts steer our thinking. Now, I am a huge proponent of allowing your intuition (your gut feelings) to play a role in guiding you, but I will caution you: if you allow your feelings to steer your thoughts and you are not suitably aware of what those emotions are telling you and why, you may reach a conclusion about an idea that has no basis in reality. Third, we must be open-minded. I cannot say this in any more simple way: question everything. Look for evidence that disagrees with what you think. It is very easy for us to look for information that supports what we believe, what we want to be true, yet ignore facts that contradict our viewpoint. This is called confirmation bias. Finally our thinking should be informed by evidence. What is evidence? Our dictionary reference tell us that the legal system considers evidence to be, “data presented to a court or jury in proof of the facts in issue and which may include the testimony of witnesses, records, documents, or objects.” I like to think of evidence as things that we can prove through experimentation, through experience, or through research.
Many times in your life you will come across “facts” that end up being incorrect. This is where the open mindedness becomes critical; if you are confronted with rational evidence that was obtained in a disciplined way and it contradicts what you already believe to be true, you must keep an open mind and explore it. You don’t need to jump ship and believe the new information just because it seems as though its better; you need to examine it, evaluate how the author or scientist came to his or her conclusion and see how it fits with what you have already learned. An open mind is perhaps on of the most challenging things to maintain when we try to be critical thinkers. Like the quote from the great cosmologist Carl Sagan we began with, this is no easy task. To hold two or more seemingly contrary ideas in mind and evaluate them to ascertain where the truth lies is a difficult task. It takes practice, discipline, and the understanding that what is objectively true often lies somewhere between the ideas.
Let’s do our own experiment. Let’s contrast a myth (an unprovable explanation) of creation with a theory (an explanation supported by falsifiable evidence) of human evolution. In this case I would like to take a creation myth of the Quiché tribe of Guatemala. I’ve read and heard this story in a few different ways, and I will tell it to you in my own way. You can find several versions with a quick Google search.
In the beginning there was nothing except for Tepeu and the feathered serpent, Gucumatz. They sat together and anything they though came into being. They thought the sun and the moon, the earth and the planets, they thought the land and the sea, and the animals and the fishes. They thought men of clay, but these creations fell apart when they thought of rain. So the gods sent a flood to wipe out the clay beings. Then with the help of the mountain lion, the raven, and the coyote they thought of a pair of men and a pair of women. These people pleased the gods and became the parents of all Quiché.
It is human nature to use our large brains to explore why, how, and what our world is all about. Primitive people who did not have the benefit of the wealth of science we now know to be factual tried to understand how and why they came into being. In the absence of evidence we make up stories that serve to explain what we believe to be the case. This is perfectly normal. What we must realize though is that as our access to facts increases we must remain open to adjusting what we believe to be true.
The current thinking among cosmologists is that our universe sprang into existence approximately 13.5 Billion years ago (give or take a few hundred thousand years). That current hypothesis is that the whole universe was condensed into a small, hot ball of energy and matter that was held together by tremendous gravitational forces (this is referred to as a singularity). Eventually the matter and energy were compressed to the point that they overcame the force of gravity and exploded outward in what has been called “The Big Bang.” Why do we say that the universe is 13.5-13.7 Billion Years old? Using the science of physics we can determine based upon wave lengths of light how far away light that is reaching us emanated from. Our current best understanding is that light from the edge of the known universe is approximately 13.7 Billion light years away. A light year is a measure of distance, how far light can travel in a year, and is approximately 9.5 Trillion kilometers (or 5.9 Trillion miles). Put another way the sun is approximately 93 Million miles from the earth and the light from the sun takes just under eight and a half minutes to reach us.Why didn’t the Quiché make up a story that reflected this idea? Echoing an idea of Richards Dawkins, we are limited by our geography.
Critical thinking is, “disciplined thinking that is clear, rational, open-minded, and informed by evidence.”
Human beings like us think in a world where rocks are solid, gravity effects how we are able to move around and over objects, and where time is measured by the light and dark cycles of our planet spinning on its axis and by the change of seasons as our planet makes one full revolution around the sun. We are not “wired” (we did not evolve the neural connections) to comprehend just how far away the sun is, let alone the speed of light. That’s why cosmology (along with many other sciences) is the realm of scientists who can use the abstract language of mathematics to express themselves. We simply don’t have the ability to visualize these ideas, and neither did our ancestors. If I ask you to imagine how long it will take you to walk ten miles you will be unlikely to be able to do it unless you have one of two things, experience or mathematics. I know how long it will likely take me to walk ten miles because I have done it many times and with a vague idea about the terrain and the weather I will likely come up with an estimate that is fairly accurate. In the same way if I told you that a thirteen year old boy who is reasonably healthy will walk about 2.7 miles per hour you could do some simple division and find that it will take you around three hours and forty minutes. However to actually go and test your idea (experiment) you would need a known distance course, and a reliable watch. If I simply sent you out to walk for three hours and forty minutes across a barren landscape with nothing to judge time but the sun it is unlikely that you would maintain a constant pace or cover the prescribed distance. Again, we just don’t have the mental faculties to estimate these things without experience.
For our friends the Quiché, and for countless other people who have created myths to explain how the world works it is reasonable to say that they were doing the best they could with the knowledge, skills, and tools they had. We are the beneficiaries of (at least) two hundred thousand years of human evolution and fifteen thousand years of culture and language. We must learn from the mass of this accumulated knowledge while always keeping our minds open for new information and testing the ideas and beliefs we have to see if they fit with reality.