On the Vagueness of Species, Part 2: On the Vagueness of Organisms

Above we see a video schematic of Hepatitis B, one of the smallest human viruses at 42 nm. Whether viruses are living things or not has been a matter of debate. Requiring a living, much larger host in order to reproduce is not exclusive to viruses.

The presence of vagueness, of border cases, among organisms between living and not-living things has been a source of frustration for some biologists. If we require of our concept of reality a rigid, medieval essentialism, like that of some who assert the reality of hard edged taxa in dividing species, we are going to be frustrated at the lack of a clearly defined border between life and non-life.

Why? Because life, like most of the categories of human experience, is a vague category.

Unfortunately, there are those whose tolerance of vagueness is very poor. Scientific American blogger Ferris Jabr is one. Faced with vagueness, he denies the category. This makes for interesting reading, given the way the pig of absurdity is dressed in well written prose.

The problem is the promiscuity of skepticism about the world when exact boundaries are elusive to scientific investigation. Let's look at an example: the air we breathe.

Does the air we breathe exist? It appears it does not. If we look at air at the atomic scale, there are only molecules in constant motion, and each individual molecule lacks all of the qualities of our air, except mass. Most of the molecules, which are made of a pair of nitrogen atoms, cannot be used by the body for its metabolism, and we would thus suffocate if we tried to breathe those atoms alone. Furthermore, there is no boundary to the atmosphere we can place in any exact sense. As we ascend in altitude, the air thins more and more, but there is no exact, distinct point where the air ends. Without a firm boundary between air and not-air, the atmosphere cannot be a real thing: it is a mere artifact of our language. The air we breathe, therefore, does not exist.

Using an extension of this argument, it is easy to "prove" that the Sun, the planets, the solar system, and the galaxy do not exist. We merely need to point out that such things are very different from their components and that they have a poorly defined physical boundary.

The fallacy of claiming that all the properties of a category (life) must be the property of its components (individual organisms), including its boundary cases, is a type of fallacy of division, also called the modo hoc fallacy. The fallacy of claiming that a vaguely defined thing cannot exist is called the continuum fallacy, which is Ferris Jabr's fallacy.

(HT: Bill Vallicella).