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.

Particulars and Universals

The problem with names is that they can always be applied to more than one thing. But the existence of unique individuals is self-evident. It is these two facts that create a puzzle for philosophers. Anything that can be applied in many cases is a universal. But something that is unique is a particular. But why should we believe in particulars at all if particular have nothing that makes them unique?

Any name at all can be applied to many things. This is not the claim that every name actually does apply to many things, but only that all names can potentially apply to many things. What seems to be strongest counter-example is names that we give for individual things themselves. The strongest example of these are personal names. So lets suppose that we know “Stephen”. He is a particular individual having a particular history. The name”Stephen” that I use applies only to him. But what makes this name apply to a particular individual? We know that Stephen could have had a different history. He might have been an only child, never attended university or lived in a different country. We might claim that it was necessary that he had the same parents, but this is nothing unique as I have the same parents as well. We might suppose that it is necessary that he have the particular genetic origins that he had. But if a had identical twin brothers with his genetic code, neither of them would be Stephen. (If one of them were, then which one is it?) So it seems that there is nothing about Stephen that makes him unique – nothing that makes him distinct from a copy of himself.

Without his history, memories do not make him unique. Without his genetic code or other information, neither parents nor family make him unique. But if the very things that make him different from other human beings are not enough to make him unique, then what could make him unique. It seems that nothing at all makes him particularly different.

On the other hand, it is self-evident that particular things exist. The idea that no individual humans, forks, planets or dogs exist is absurd. Without individual things, there is no reason to believe in any universal at all. So rejecting the existence of particulars as such is irrational.

But these conclusions form a contradiction. If there is nothing at all that makes Stephen different from a copy of himself, then there is nothing that makes anything different from a copy of itself. Stephen is the preeminent example of a particular. If he is not really a particular, then nothing else is either. But it is self-evident that there are particulars. All self-evident sentences are true. Therefore, there are particulars. But then there both are and are not particulars.

Before continuing to examine this issue and come to a resolution, it is helpful to determine if this is the only problem with particulars and universals. This is problem with the existence of particulars. But there could be other kinds of problems. One of these has to do with the existence of universals.

I will discuss that problem next.