[tdwg-content] New terms need resolution: "Individual"

[Hilmar Lapp]

On Jul 14, 2011, at 12:13 PM, Gregor Hagedorn <g.m.hagedorn at gmail.com> wrote:

>> But aren't individuals populations taxa etc etc all biologicalEntities?
> 
> Yes, but so, I believe, are ecosystems, organelles, enzymes, and
> probably much more.

Good observation. You could actually use this as a basis for first crafting a definition of the term, and worry about the label you'll assign to it later. For example, using the genus-differentia pattern, you can start with "<X> is a biological entity that <Y>", where <X> is the label, to be deferred to later, and <Y> are the criteria (properties, or to be more precise, property restrictions) that distinguish the class of things we want to define from all other things that are also biological entities. These criteria would need to be chosen such that they apply to *all* members of the class (not only to some), and while a subset of these properties may apply to instances that are not members, there is no instance to which the conjunction of properties applies but that is not a member of the class.

Frankly, I'm not even sure that this is the best place to start for the definition. Perhaps it's better to take one step back further, and enumerate a variety of example instances of biological entities that we all agree should be in the class, and a contrary enumeration of example biological entities that we all agree should not be in the class. If you include less obvious and possibly controversial ones in these lists, it may help to narrow down what the differentiating criteria really are. And while this exercise may sound trivial, it hasn't been done yet as far as I'm aware, and from a number of the posts in this thread I sense that there is actually not consensus on which side of the divider the border-cases go. And you can't hope for consensus on the label (or the definition) if there isn't first consensus on how we want the instances classified.

Just to throw in an example, I might argue that at least some organelles should actually be among the biological entities included in the class. Some organelles have their own genome and evolutionary history, and were once independent organisms. If we accept this, then we might say that biological entities to be included have a genome or a pool of genomes with a (shared in the case of a pool) evolutionary history, and those to be excluded do not. This would exclude vacuoles from the class, but include plastids, viruses, cows, and buffalo herds. 

-hilmar

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