ARCHIVED—Periodic laws, atomic theories and epistemology
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- How can I know? Let me count the ways.
- The use and abuse of classification systems
- How am I supposed to know that?
- Where can teachers learn about epistemology
Ross Sheppard High School
There are few things people take more for granted than the origin and nature of their knowledge. We use what we know when we need it and curse when we don't know enough. Knowledge is the common currency of our intellectual world and we tend not to wonder about it any more than we do about money, except, of course, in times of crisis.
Epistemology is a discipline whose practitioners wonder about knowledge all the time, rather than just when knowledge becomes problematic. Epistemology is the rules of the knowledge game teachers play with their students in every classroom. Practitioners consciously concern themselves with questions such as: What is knowledge anyway? Where does our knowledge come from? Where and when is it appropriate to use it? Frank Jenkins is one of a few pioneering teachers who introduce high school students to epistemology, usually a university-level subject. As he tells us below, high school students often ask questions that sound much like the ones philosophers pose.
There is more to epistemology than speculative issues, however. Dr. Jenkins also explains how epistemology can help students become more effective learners.
I started using epistemology to help my students learn mostly because I think it helps them to learn better. The more ways someone knows something the better they know it, but first you have to know what ways of knowing to look for. Beyond that, there are three factors that led me to apply it in chemistry classes.
First, chemistry, as I will explain later, is particularly well suited to introducing epistemological questions in a way that is immediately relevant to what students are studying.
Second, there is the troubling tendency of high school science textbook authors to frame knowledge in purely theoretical terms. This leads students to think that theories are the only things we really know or represent the best way of knowing. In fact, much of what we know is only empirical concepts — generalizations or laws based on empirical observations.
Finally, I, like all teachers, need to deal with a perennial student question: How am I supposed to know that? I have heard that question more than once in my career and have sometimes had to struggle to answer it or, in my less inspired moments, have tried to gloss over it.
Chemistry is easy to link with epistemology because classification systems are so important. We use a variety of ways to group and describe chemicals — metals and non-metals, acids and bases, solids, liquids and gases. Classifications like these are a particularly slippery kind of knowledge. Virtually every classification system breaks down in some circumstance and that leads us to question how we really know something if our knowledge is based on something uncertain.
Consider, for example, the periodic table of elements.
In chemistry you may teach the periodic law by referring to a whole series of subatomic theories. Students learn about the periodic table by studying things that are not observable — atoms, molecules, electrons and intermolecular force field theories. If we constantly teach this way, many of our students come to think that theoretical learning has a higher value than empirical knowing, and even comes first.
Historically, however, scientists originally created the periodic law through a series of empirical observations. In fact, two 19th century scientists figured it out simultaneously. Lothar Meyer, working in Germany, arranged the 57 elements he knew about according to atomic masses and generalizations about the properties of the elements, and left spaces for elements that had not been discovered yet. Meanwhile in Russia, Dmitri Ivanovich Mendeleev did something similar using the chemical properties of the elements. He not only left blank spaces for the missing elements but he also predicted what the chemical and physical properties of these elements would be when they were found. These predictions were tested and verified 16 years later and led to the acceptance of Mendeleev's periodic law.
Meyer and Mendeleev knew the periodic table in a different way than we do, but no one could say they didn't know it because they weren't familiar with the theoretical explanations that other scientists came up with half a century later. I like to show my students that we can know the periodic table either empirically or theoretically, but that they may find, depending on their goals, that sometimes one way is better than the other or that they are complementary. Historically, the empirical way of knowing most often led to the theoretical and the theoretical sometimes changed the way we understood perceivable things.
Consider, for example, metals and non-metals. This distinction was used to classify elements in the earliest versions of the periodic table. It was — and still can be for some applications — a useful initial way of classifying elements. But we have trouble with the empirical definitions of metals and non-metals when we first encounter carbon as graphite, which is dull and brittle but conducts electricity. It does not easily fit into our normal understanding of metal.
Chemistry is an ideal subject for introducing students to epistemology precisely because we often run into issues like this. The division between metals and non-metals does not exist in nature. It is an artificial classification system that was invented by human beings. As Einstein would have said, "It is a free creation of the human mind." But then, of course, we have to wonder how we know anything if our classification systems are artificial. How can something created by human beings apply to the real world?
I always ask my students why we classify things. Well, we do that to help us organize our knowledge. Students begin to see that these concepts (and generally, the earliest organizing concepts are classification systems) are for our convenience. All classification systems exist because they are useful for doing chemistry, and they evolve.
My students come to see that there is no such thing as certain human knowledge. Our classification systems and an awful lot of human knowledge that comes from the classification of stuff are human inventions. This is very different, however, from saying that we don't know anything. Of course we know things, but we never know them absolutely. We can build upon our understanding and we can reduce the degree of uncertainty, but we can never reach something called absolute knowledge. I always tell my students to be wary of those who lay claim to absolute knowledge — these are the dangerous people in our society.
That is important because in science we do not acknowledge this uncertainty often enough. At high levels, such as in journals of theoretical physics, it is done but in high school chemistry it is not. When students read a Grade 10 chemistry text, they do not often see any acknowledgement of the fact that a particular theory is just one way of understanding the world. What is more, if the chemistry teacher just teaches the subject without thinking about the hidden epistemological messages, he or she will do the same. It is impossible to teach without conveying a view of the origin and nature of the knowledge being presented.
The situation is analogous to values. Even if you never say a word about your value system in class, you will inevitably convey that value system to your students because everything you do is framed by those values. The way you respond to questions, how strict you are about late work, and the amount of time you have for students who are struggling, all demonstrate your values to students. Epistemology is the same way. You have a series of core beliefs about what counts as knowledge and you convey those core beliefs to your students in everything you do.
Suppose, for example, that I value truths that can be backed up with mathematical formulas. Even if I never tell my students this, they are going to see from the way I treat the application of mathematics to chemistry that this is what I think really matters.
The truth, of course, is that we all teach students things that we know are not really the best concepts. When primary school teachers introduce students to arithmetic, for example, they teach numbers knowing full well that they are giving a very incomplete notion of them. Later we shatter these simplistic notions with concepts such as fractions, rational and irrational numbers, and integers. If they go far enough in mathematics, students will eventually run up against imaginary numbers!
We do something similar in chemistry when we teach students to distinguish between acids and bases using concepts we know are incomplete. When we teach a more complete theory, students sometimes ask why we didn't just teach them the second theory in the first place. The simple answer is that this way is just a useful way to teach. A slightly deeper — and more honest — answer is to get into epistemology, to tell students about the nature of knowledge, its evolution and some of its limitations. (And, as every chemistry teacher knows, this second theory of acids and bases is also inadequate. There is another more complete, but still uncertain, theory coming at the university level.)
Epistemological enquiry has a very practical purpose in the classroom. Consider our original student question — How am I supposed to know that? What do you say to this student? One interesting response is to turn the question around. Every student knows that H2O is water. But how do they answer the question when you ask them how they know that?
The answer is actually terribly obvious, perhaps too obvious. They know it because they have memorized it. That, of course, does not seem good enough. Many people, for example, also know that E=mc2, although most would be hard pressed to explain what it means.
One blackboard in my classroom never gets erased, and on it I keep track of these epistemological concepts. I include "memorization" on the list as one of the ways we can acquire knowledge. It is a way of knowing and a perfectly good one in the right place. After all, how do you know your name?
Another way of knowing is to look things up — a referenced way of knowing. If students have a periodic table on the inside cover of the textbook then they can use it to look up all sorts of useful information.
Two of the more important ways of knowing for chemistry are empirical and theoretical. Empirical knowledge is particularly challenging because we all use it, not only in chemistry but in the rest of our lives as well, without really understanding it. I "know," for example, that paper burns if I heat it to a certain temperature and oxygen is present. When I say this, I really mean that I have seen this happen often enough to conclude that it will keep happening. But what am I doing when I create this concept? Am I generalizing from a series of cases or am I applying some rule? I also discuss these issues with the class and include them on my special blackboard.
Understanding that there are different ways of knowing can be a tremendous relief for students because sometimes they don't need to know things theoretically. Often, we teach empirically but do not expect students to understand the theory behind the knowledge. Consider, for example, redox reactions. From doing experiments, my students have come to make an empirical generalization about these reactions. They know that if an oxidizing agent is above a reducing agent in the redox table we have constructed in the laboratory then the two will react spontaneously if brought together. For many, this does not seem like enough. As with memorizing that H2O is water, the students feel like they ought to know about redox reactions some other way. But when I tell them, that this is how you are supposed to know it, they relax.
Unfortunately, many professional philosophers would make poor arithmetic or chemistry teachers. They want to teach everything about epistemology or nothing. For this reason, they are not very helpful or encouraging for high school teachers who want to teach only some initial epistemological concepts.
In high school, we don't want to overwhelm the students with too much epistemology for the same reason we use only a partial understanding of the concept of numbers to teach arithmetic to primary school students: we would only confuse them. If you go to the local library and look up "epistemology," you will most likely end up with something far too involved to be useful to you.
Fortunately, a group of science teachers in Britain has provided a practical alternative. The Association for Science Education has published a series of books called Science and Society, one of which, The Nature of Science, provides a great overview of epistemology in 67 pages.
I recommend the book for any science teacher. Even if you don't do anything with epistemology, the book will add to the ways you can explain concepts to students. It will increase your arsenal of teaching and learning techniques. Ideally, I hope you will pass the ideas along to your students as well.