Biology Reference
In-Depth Information
Systems biology should aim to find more of the above clarifying connections
between particular part-whole mechanisms for behavior, which possess gener-
alizable features at the systemic level.
8. EXPLANATORY PLURALISM: INTRALEVEL AND
INTERLEVEL THEORIES
The importance of levels of organization, however difficult to define, cannot
be underestimated in systems biology. As some levels of organization in living
organisms are relatively autonomous, they are home to their own intralevel
theories. These theories are valuable, but the inherent danger is that focusing
too much on the autonomy of all levels of organization results in specialists
who know a great deal about their own level, but quickly consider themselves
nonspecialist outside their area of research. And of course one has to be modest
in the light of the overwhelming body of knowledge that is available at each and
every level of biological organization. This might explain why so many scientists
stick to their own field of research, it seems. At the same time, it implies that
there is more than enough space for connections and that it is worthwhile to seek
such connections. In this sense, system biologists should be (become) generalists
and should endorse a multidisciplinary approach. Connecting levels (e.g., via
mechanisms) without eliminating the higher level (reduction without leveling)
and without completely downplaying the lower level is very much possible and
should be pursued in systems biology. In its focus on the interactions between
the parts of a system, systems biology endeavors to find such connections.
Several authors have stressed the importance of nonreductionist interlevel type
of explanations (Fell; Richardson & Stephan; Shulman; Westerhoff & Kell). In
short, we are in favor of an explanatory pluralism that incorporates intralevel as
well as interlevel theorizing.
9. WHAT IS LIFE?
Erwin Schrödinger asked this question first in a now classical topic (Schrödinger,
1944). Many biologists and philosophers of biology refrained from giving a def-
inition of life, but instead gave lists of characteristics of life. In this topic, several
authors took up the issue. Hofmeyr did so by presenting his MCA (metabolism,
construction, assembly) system (not to be confused with Metabolic Control
Analysis), combining Rosen's MR system with Von Neumann's universal con-
structor. Hofmeyr sets out to make self-fabrication of cells formally intelligible
in terms of the functional organization of a generic set of processes common
to all organisms. Essential in his reasoning is the unassisted self-assembly of
