Taxonomy (Or Why Modern Biological Categories are Wrong)

cladeAristotle was the first to systematically lay out various living things in the world. According to him, they could be divided into three categories: plants, animals and rational beings (humans). Insofar as biology is concerned, human beings are animals. Therefore, there were two biological categories: plants and animals. Carl Linnaeus extended this knowledge to cover many new kinds of plants and animals, and created more divisions below that of plants and animals. Many of our modern biological categories come from him. The highest division was the kingdom and there were two kingdoms: plants and animals. In 1866, Ernst Haeckel suggested that simple single celled organisms form a third kingdom that he originally called Monera. (He later called this kingdom Protista.) His reasoning behind this change was that biological divisions show historical ancestry (common descent). Modern taxonomists have followed this new pattern and begun a program of categorizing biological things according to ancestry. This is wrong because it is contrary to the purpose of biological categorization.

There are thousands and thousands of different kinds of biological things. There are also many possible ways to categorize them. We might categorize living things by considering how we use them. So weeds refer to plants that we do not want, trees refer to large plants that provide shade, vegetables are edible plants with a similar kind of taste and fruits are plants that have sweet parts. This kind of categorization does not help us understand the living thing. It simply helps us categorize the living thing according to our purposes for it. In fact, any external categorization will not help us understand the living thing. I might name plants according to where they are found, whether I like them, where I bought them or what they can be used for. But these things may vary even if the plant (or animal) stays the same. Furthermore, even if these things do not vary, the explanation for why they do not vary includes knowledge not related to the living thing in question. For example, the reason why pineapples are edible partially has to do with the human digestive system. Finally, even the knowledge about the living thing itself does not unify our knowledge of that living thing. So no externally based categorization scheme is proper if our goal is understanding the living thing itself.

Categorizing living things by their ancestry is an external categorization scheme. The explanation why two living things were placed in the same category would be an external fact (that it is the best fit for those two individuals given the rest of biology). Although historical knowledge is invariant across researchers, it includes both facts about the living thing itself and facts about the rest of the living things that happen to live in the world. Secondly, knowing that dogs and wolves share a common ancestry does not unify our knowledge of dog or wolf biology. Knowing that both dogs and wolves are mammals (and that being mammalian is more fundamental than being a dog or a wolf), does unify our knowledge of either a dog or a wolf.

When we categorize living things we must begin with what is most fundamental, and work our way to what is least fundamental. What is most fundamental to a living thing is the reason why it is alive. Without that, it would not be a living thing at all. Everything else that a living thing does supports the life of that living thing first of all. Least fundamental are the parts of the living thing that can change without harm to that living thing – such as the length of hair, the color of hair or the growth of new branches. Nowhere in this scheme is there room for facts about the ancestry of living things.

The purpose of categorizing living things in biology is to organize them in order to understand them in themselves. The purpose requires categorizing living things according to differences in those living things beginning with the most fundamental differences. Since the differences between living things are purely internal, there is no room for history. Therefore, classification schemes such as cladistics that are based on historical relationships between organisms are universally wrong.

Methodological Naturalism, Science and History

evolasnoanswerMethodological naturalism is usually understood to be the idea that a subject will be investigated as if supernatural causes do not exist. This is often considered to be a part of science, and therefore theories such as intelligent design cannot be scientific. While intelligent design theory is not a scientific theory, this issue should still be resolved in order to better understand the place and necessity of methodological naturalism.

Science deals with the powers, dispositions, structure and composition of natural things. Science is the study of a thing according to the kind of thing it is. It does not deal with particular things as particulars. History, on the other hand, deals with particular things as particulars. For this reason, history deals with the past of particulars and their relationships to other particulars. Most history departments only deal with written human history. However, prehistory (meaning prior to written history), paleontology and historical science are all forms of history. Because the basic data of these disciplines is found by scientific research or tools, many of the researchers are scientists. It is not surprising that many of these scientists think of their work as scientific rather than historical.

But there are some key differences between scientific work and historical work. The first difference is that historical study is a matter of probability. Any and all historical theories are supported by evidence that is not deductive in nature. We might consider them to be inferences to the best explanation, or Bayesian probabilities but they cannot be deductions. The second difference is a result of the first one. Any historical theory may be replaced by a theory that completely rejects the central points of the first theory. It might be unlikely, but such a thing is always possible. Third, historical theories are not based on experiments, – repeatable or otherwise – nor are historical theories subject to empirical verification. The evidence for a historical theory may be empirical, but the theory itself is not. These differences mean that one cannot simply treat science and history as similar disciplines.

Methodological naturalism is necessary in science because science requires that as a precondition of investigating natural things. Suppose someone claimed that gravity was an act of God. Such a thing might be true (in some Eastern religion perhaps), but if science is to investigate gravity, it must assume that gravity is not an act of God. First, there is no possible way to rule out of the act of God hypothesis. In this way, it is much like supposing that our entire lives are illusions, that the universe is irrational in its foundations or that natural things have nothing in common with each other. Each of these things are simply assumed to be false by the mere act of scientific investigation. This is the second reason. The mere act of scientific investigation supposes that we can understand, investigate and empirically determine what the causes of something are. But we cannot do this with acts of God. Therefore, methodological naturalism is both unavoidable and necessary for science.

Methodological naturalism is not necessary for history. History does not investigate by empirically determining anything. Although history does seek to answer questions about the past, it requires only that the past be rational. Rational simply means that there is a reason. So if something did happen that were an act of God in the past, then as long as that act had a reason, history can investigate it. Hume’s arguments against miracles are an abject failure. Much of the modern animus against miracles is motivated by those reasons. Therefore, moderns have no good reason to reject miracles as such. Each miraculous case must be taken on its own merits and the evidence considered individually. Having said that, miracles cannot be a common occurrence in history. Their occurrence has to be low enough that they do not alter science research. That is fairly easy though, miracles must be less common than one part in five – enough to lose statistical significance.

This result means that miracles cannot be removed entirely from consideration in the historical sciences. They are a division of history rather than science, and what applies to history in general applies to them. However, evidence must be found to support them in particular cases. While this is not directly relevant to intelligent design theory, it does affect creationism. Since many intelligent design theorists are also creationists, this is an argument that they advance as creationists. (It is possible to believe in intelligent design theory and claim that aliens are responsible for the features that were caused by an intelligence.)