Biology Reference
In-Depth Information
on organ systems, it might involve the hippocampus. At a resolution focused on
cells, it might focus on cells within the hippocampus. The key thought is that,
even with a tolerance level assumed, we may seek explanations with different
explanatory depths. These are what we think of as different degrees of resolution.
Let us try this with a model from cell biology.
In Fig. 1, we imagine some cellular behavior to be mechanically explained
belongs to some level of organization L (e.g., the cellular level, or a molecular
level), and it is described by a certain grade of resolution G (e.g., as behavior
of a cell or as the behavior of a molecular system).
To construct a mechanistic model, we need to describe the system in terms of
parts and processes that are expected to be sufficient to explain some behavior
(with some degree of precision). There are typically various grades of resolution
possible in the way we describe the system. These can be thought of as focusing
on more or less detail, as if we could zoom in or out on the system revealing
more or less about what is happening within the system. So, for example, a
bacterial culture can be thought of as a culture, or as a collection of cells,
which in turn can be thought of as a collection of biochemical networks or as
a collection of macromolecular systems. This is a matter of redescription rather
than reduction. We redescribe the culture as a system of cells or as a set of
macromolecular systems. We are not reducing the system behavior to cellular
Grades of resolution
G+1
G G-1
G-3
Example:
cellular behavior to be mechanically explained
Level of single cells
L+1
L
L-1
L-3
Behavior to be explained is at L
Figure 1
Grades of resolution and levels of organization.
There are two independent dimensions: one concerns levels of organization, and is characterized
by a change in the characteristic entities (e.g., organisms, single cells, molecules); the other
concerns the resolution with which they are described (e.g., a cell may be described relationally
as a component within a system of cells, or as a network of metabolic pathways, or as a system of
molecules). One can change the grades of resolution without changing levels of organization. All
of these are descriptions of the same system, and hence at the same level of organization, though
the system is described differently.
