2. A Non-Reducible Hierarchy of The Sciences
Most scholars in theology and science, while accepting the importance
of methodological reductionism in science, view epistemic reductionism and
reductive materialism as undercutting the credibility of higher-level
disciplines and supporting the conflict model between science and theology.
To counter this, they typically argue that the academic disciplines form a
non-reducible hierarchy, starting from physics at the bottom and moving upwards
through chemistry, biology, physiology, the neurosciences, the behavioral,
psychological and social sciences. The ordering of
the hierarchy reflects the increasing complexity of the phenomena being
studied; more importantly, it allows both for rules of constraint and genuine
emergence. Constraint implies that the laws, processes and properties at
lower levels, such as physics and biology, constrain the laws, processes and
properties at upper levels, such as psychology or ethics. Thus the laws of
chemistry must be consistent with, and not contradict, the laws of physics. Emergence
implies that upper levels are partially autonomous; they include new laws,
processes and properties which cannot be fully reduced to, explained away by,
or derived from those of the lower levels. The ordering of the sciences in the
hierarchy corresponds roughly to the rise of ever more complex physical and
biological systems during the history of the universe, including galactic,
stellar and planetary development, and eventually molecular and evolutionary
biology.
As early as 1979, Arthur Peacocke described such a hierarchy
of disciplines, drawing on the writings of M. Beckner, M. Polanyi, and E. Nagel
along with Ayala and T. Dobzhansky.By 1993 he had foliated the hierarchy into two dimensions: vertically it
consists in four levels of increasing complexity (the physical world, living
organisms, the behavior of living organisms, and human culture) while
horizontally it depicts systems ordered by part-to-whole hierarchies of
structural and/or functional organization (eg., in biology: macromolecules,
organelles, cells, organs, individual organisms, populations, ecosystems).Peacockes analysis undoubtedly reflects the broad consensus of the scientific
community.
A key issue, though, is the place and role of theology in
the hierarchy of knowledge. Peacocke tends to place theology at the top of the
hierarchy. As the all-inclusive study of God, humanity and the world it cannot
be isolated from, but instead it should seek to integrate, all that we know
from the rest of hierarchy. Moreover, by putting theology at the top, it will
be maximally constrained by the rest of human knowledge. Moreover, by placing
theology at the top of the hierarchy, it is maximally constrained by, and
responsible to, the discoveries and conclusions of the other disciplines.In a recent proposal, Nancey Murphy and George Ellis suggest that the hierarchy
be modified into the shape of a Y. The hierarchy starts with physics and
moves up to chemistry and biology. Here, though, the hierarchy splits, with one
branch leading to levels which study more encompassing wholes, including
geology, ecology, astrophysics and cosmology, while the other leads to levels
which study more complex systems, including psychology, the social sciences,
and ethics. An inverted Y then rejoins lines from cosmology and ethics to end
in theology. A crucial
ingredient of their argument is that the higher levels in the scheme complete
the lower levels by offering answers to key questions raised by them. This
gives theology an essential role in the overall system: A single theory of
divine purpose answers the ultimate questions arising from each branch of the
hierarchy.
Causal reductionists, however, might allow for a hierarchy
of disciplines while still claiming that all causality is bottom-up. Even if
higher level theories describe the regularities of their phenomena in
apparently irreducible ways, the possibility of causal reductionism remains, as
exemplified in the mechanistic philosophy of the 18th and 19th centuries.To counter this, a variety of scenarios have been explored in which processes
at upper levels actually do influence processes at the lower levels. These
include top-down causality, whole-part constraint,and supervenience.(See Part 2, A, 2, Divine Action)
Contributed by: Dr. Robert Russell
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