25 No. 3
May - June 2003
I push my hand down onto my desk it does not generally pass
through the wooden surface. Why not? From the perspective
of physics perhaps it ought to, since we are told that the
atoms that make up all materials consist mostly of empty space.
Here is a similar question that is put in a more sophisticated
fashion. In modern physics any body is described as a superposition
of many wavefunctions, all of which stretch out to infinity
in principle. How is it then that the person I am talking
to across my desk appears to be located in one particular
general answer to both such questions is that although the
physics of microscopic objects essentially governs all of
matter, one must also appeal to the laws of chemistry, material
science, biology, and other sciences. Chemistry for example,
may be essentially governed by the laws of quantum mechanics,
but in order to study the nature and transformation of matter
at the appropriate chemical level, one needs to appeal to
laws of science other than just quantum mechanics. This realization
that chemistry is not fully "reduced" to quantum mechanics
has been one of the main motivations for the recent resurgence
in the philosophy of chemistry.
Tim Lenoir, Stanford University
the turn of the 20th century chemistry was at the heart of
philosophical issues in science. For example, it was almost
exclusively chemists who conducted the atomic debates that
followed the influential work of John Dalton. While some of
them regarded atoms as entities that actually existed, others
thought about them as mere convenient fictions. But following
the discovery of radioactivity and the birth of quantum theory,
the atom was snatched away from the chemist and the philosophical
focus switched to physics, which had by this time also experienced
the Einsteinian revolution in the study of space and time.
Chemists began to be seen as people doing applied physics.
As Dirac famously claimed, all of chemistry had been reduced
to physics and all that remained was to clear up the details.
course, the field of computational quantum chemistry, which
Dirac and other pioneers of quantum mechanics inadvertently
started, has been increasingly fruitful in modern chemistry.
But this activity has certainly not replaced the kind of chemistry
in which most practitioners are engaged. Indeed, chemists
far outnumber scientists in all other fields of science. According
to some indicators, such as the numbers of articles published
per year, chemistry may even outnumber all the other fields
of science put together. If there is any sense in which chemistry
can be said to have been reduced then it can equally be said
to be in a high state of "oxidation" regarding current academic
and industrial productivity.
in the early 1990s a group of philosophers and chemists with
philosophical leanings began publishing articles aimed at
exploring the question of the alleged reduction of chemistry.
Soon thereafter the International Society for the Philosophy
of Chemistry was created. Its official journal, Foundations
of Chemistry, has begun its fifth year of publication. Another
international journal, called Hyle, also devoted to the field,
had been launched earlier on the Internet but is now also
available in paper form.
. . there has been an ongoing debate about just how
much quantum mechanics should be deployed in the teaching
of general chemistry.
has been a good deal of interest from the chemical education
community, not surprisingly since educators regularly face
philosophical choices as to how to best present the contents
of chemistry courses and what kind of emphasis should be pursued.
Returning to an earlier issue, there has been an ongoing debate
about just how much quantum mechanics should be deployed in
the teaching of general chemistry. Detailed studies on such
questions are beginning to emerge from work in philosophy
of chemistry and are being seriously considered by educators.
philosophers of chemistry are also concerned with many other
issues beyond the role of quantum mechanics. Philosophers
of science have realized for some time that there has been
too much focus on purely theoretical and logical aspects of
science. There has been a gradual turn towards the study of
scientific models and approximations as well as the nature
of semi-empirical methods and instrumental techniques. In
all these areas chemistry has begun to provide a rich selection
of new case studies, especially given the less deductive nature
of chemical theories as compared with those of physics.
recent influx of philosophy into chemistry also promises to
clarify another important issue in chemical education. In
recent years many science educators, and especially many chemical
educators, have begun to support an approach referred to as
constructivism. These authors correctly point out that students
come to chemistry classes from a wide variety of backgrounds
and with many preconceptions. They claim that it is a mistake
to ignore the fact that students have constructed their view
of scientific facts such as the nature of acids and bases
to take just one example.
chemical educators have even fallen prey to the related
post-modern position of relativism without realizing
that this is both self-defeating and essentially anti-scientific
in their eagerness to embrace this admittedly more enlightened
educational approach, some of these chemical educators have
unwittingly aligned themselves with constructivist claims
about the manner in which mature scientific knowledge is arrived
at by mature scientists. The claim of constructivists is that
scientific knowledge is somehow socially constructed rather
than being discovered. The dominant school of chemical education
may therefore be on the wrong side of the recent and notorious
Science Wars debate. Some chemical educators have even fallen
prey to the related post-modern position of relativism without
realizing that this is both self-defeating and essentially
anti-scientific in spirit. If, as relativism maintains, all
paths of knowledge are equally valid then why should anyone
even want to support relativism itself in favor of any other
articles emerging from the philosophy of chemistry have now
begun to challenge the confusion that exists among some chemical
educators. The ensuing debates might serve to distinguish
between educational constructivism, which may be valid, from
constructivism about scientific knowledge itself, which very
few scientists are willing to concede to but which many chemical
educators seem to draw inspiration from.
there are ethical questions that inevitably surround chemical
synthesis and the chemical industry in general. As we all
know chemistry receives more than its share of the blame for
the environmental ills of today. One positive response from
the chemical community has been the growth of the Green Chemistry
initiative that aims to find environmentally friendly ways
of producing industrial chemicals. The approach is essentially
a philosophical one. The relationship between ethics and chemistry
is being increasingly examined by some philosophers of chemistry.
study of visualization and representation is another philosophical
issue that has come increasingly to the fore with the development
of chemistry and the parallel growth of computational power.
Chemists are rather unique in frequently needing to visualize
structures and entities that they also know not to exist according
to the dictates of physics. Atomic and molecular orbitals
are a good case in point. They are used as mathematical tools
in quantum chemistry at all levels. Their use has been undeniably
productiveas in the case of the Woodward-Hoffman rules
in organic chemistry. And yet, from the perspective of quantum
physics, any orbital is just a mathematical fiction devoid
of any real existence just like the square root of the number
minus one in mathematics.
sometimes the zeal with which chemists like to embrace models
and visualizations goes a little too far. Such was the case
about three years ago when many scientific magazines reported
the claim that textbook orbitals had been literally observed
for the first time. These excesses were quickly corrected
in the literature but the only people who took the trouble
to do so were among the more reflective chemists and philosophers
is another reason why philosophy of chemistry has been such
a recent newcomer alongside the more established study of
philosophical aspects of modern physics and biology. The reason
is partly historical and partly due to the kind of systems
one is dealing with in each of the three sciences. Of course,
philosophers of science have traditionally
concentrated on physics since it is the most fundamental science.
fundamental does not necessarily mean more important. This
is clearly seen if one thinks of biology. To living beings
such as us there is an immediate sense in which biology is
more relevant and more important than abstract theoretical
physics. In the 1950s and 60s philosophers of science
realized that they had concentrated too much on physics and
that the general principles they had arrived at regarding
the nature of science just did not apply to vastly different
biological systems. They then quickly set about developing
the philosophy of biology while completely leap-frogging over
the complex and central science of chemistry. This response
may seem to have been shortsighted in hindsight, but it is
also perfectly understandable. Biology is very different in
scale and nature from microphysics and the study of space
and time. Chemistry on the other hand shares many aspects
with physics and biology and so philosophers persuaded themselves
that a special study of how chemistry is different was not
. . it is to be expected that the philosophical study
of chemistry will eventually pay large dividends to
our understanding of science as a whole.
the time has now come for such a fine-grained approach to
philosophy of science that seeks to distinguish between physics
and chemistry, while at the same time respecting all its similarities.
Likewise, philosophers of chemistry have begun to examine
the interface between chemistry and biology. Given the richness
and complexity of chemistry, which serves to link physics
and biology, it is to be expected that the philosophical study
of chemistry will eventually pay large dividends to our understanding
of science as a whole. Seen in this way, the delayed emergence
of philosophy of chemistry is no longer mysterious but may
be a direct outcome of its frequently noted central position
among the natural sciences.
rising interest in the field was quite evident at the sixth
meeting of the International Society for the Philosophy of
Chemistry that took place at Georgetown University in Washington,
D.C., in August 2002. An audience of about 70 was able to
choose between papers given in three parallel sessions over
the course of three days. Speakers included Kovacs (University
of Kentucky), Vemulapalli (University of Arizona), Earley
(Georgetown), Scerri (UCLA), Harré (Oxford), van Brakel
(Leuven), Needham (Stockholm), Ramsey (Smith College), and
Schummer (Karlsruhe), as well as chemical educators and historians
interested in fundamental aspects of chemistry.
I would just like to mention that several excellent books
have appeared on the subject of philosophy of chemistry. It
has become clear that from being ignored in the past, this
field is now the fastest growing sub-discipline within the
philosophy of science.
Eric Scerri <[email protected]>
is a lecturer in the Chemistry & Biochemistry Department
at UCLA and is the editor in chief of Foundations of Chemistry.
The author is happy to provide references or further information
on any of the issues raised here.
last modified 29 April 2003.
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