Evolution
is almost alone among scientific ideas in the degree of controversy it
generates. Part of the reason for this is, of course, that it can be
more than a scientific theory, capable of expansion to include
philosophical claims about the existence of God or human nature. Even
if restricted to the material order, evolution inevitably has
consequences for religion, as its claims must influence our
understanding of the process of creation, and of human nature. The
anthropological and theological implications of evolution are so
profoundly felt by many that it is rare to find people who do not have
an opinion on the subject.

Indeed, it is not uncommon to find people
lacking a specialist background in biology willing to hold opinions
that contradict those of the overwhelming majority of biologists. This
is a remarkable fact. Few indeed are the well-established fields of
scientific inquiry that experience such popular resistance. The
resistance to evolution is, furthermore, not limited to a fringe of
young earth creationists. There have also been objections to evolution
put forward on sophisticated philosophical grounds.

Here, I explore the ongoing debate over
evolution. In the first part, I look at the varied meanings of the word
"evolution" explore the nature of the debate. I claim that simply
recognizing that there are multiple layers of meaning inherent in how
evolution is characterized and described would go a long way to solving
its problematic meaning for many religiously-minded people.

In the second part, I propose some key
philosophical points that I believe are essential for reconciling a
scientific theory of evolution with a Christian belief in creation in
the context of Thomistic philosophy. In the course of this discussion,
I take for granted that evolution has been demonstrated on the basis of
solid and ever-expanding evidence.

The notion of evolution in
popular use contains four key ideas, and distinguishing among the most
important of these helps to understand the nature of the controversy
about evolution, and, I think, can help many to accept its scientific
claims. Among these ideas, one is philosophical, while the other three
belong properly to the science of biology. These three scientific ideas
are common descent, the pace of evolutionary change, and the mechanisms
underlying evolutionary change.

Common descent is the most basic claim of evolutionary theory, which is that every
living thing on earth is part of a single family tree. The evidence for
this comes less from the fossil record, although it is present there,
than from homology among the structures of living beings. It is
difficult to conceive of any explanation other than common descent for
shared genetic coding of both proteins and in many cases non-translated
nucleic acid sequences, such as the segments which mark the boundaries
of genes on DNA strands or control how they are expressed. Homology is
also evident in large scale structures in living things, such as in the
bone structures of the limbs of tetrapods. The evident similarity found
among all living species demonstrates a relationship between them, and
this relationship is effectively explained by common descent from a
shared ancestor. The most basic idea of evolution is, then, a
consequence of accepting common descent. It is indeed impossible to
conceive of any idea that could possibly explain homology that is not
contrived.

How and at what pace evolution occurs are
the next two scientific ideas subsumed in evolution. Charles Darwin and
Alfred Wallace, of course, independently proposed natural selection as
a mechanism of evolutionary change, but they were not the first
to explore possible mechanisms. Jean-Baptiste Lamarck had proposed the
inheritance of acquired characteristics many decades before, and a
number of other mechanisms would gain a following in the second half of
the nineteenth century. The most important of these were mutation
theory, which was developed by Hugo de Vries and focused on
discontinuous variation in evolution in contrast to Darwin’s
gradualism, as well as orthogenesis, which held that the direction of
evolutionary change was inherent in living beings and not subject to
selective pressures.

The 20th century has seen other
possibilities suggested, the most important of which is genetic drift
by Motoo Kimura in 1968. Kimura argued on the basis of evidence
gathered from studies in molecular biology that the rate of change
found on the molecular level was too high to be accounted for by
natural selection alone, and that therefore a good deal of change is
not acted upon by selection, meaning that a significant portion of
molecular evolution takes place as neutral drift. These evolutionary
changes coming from drift can be either beneficial, deleterious, or
neutral. It is now accepted that natural selection and genetic drift
together are the dominant mechanisms of evolutionary change, although
Lamarckism is once again being considered as heritable epigenetic
changes have been observed. These mechanisms explain only the material
process by which evolution occurs, and not the ultimate causes of
evolution.

The final concept contained within the notion of evolution is the pace of evolutionary change.
Although gradualism was dominant in Darwin’s thinking, the second half
of the 19th century witnessed the rise of other opinions regarding the
pace of evolutionary change, the most important of which was mutation
theory’s large jumps. The rediscovery of genetics, with its emphasis on
clearly distinct expression of genes, gave further impetus to mutation
theory’s jumps. This changed, however, with the forging by Theodosius
Dobzhansky among many others, of the modern or neo-Darwinian synthesis
in the 1930s. This united Darwinian mechanisms with Medelian genetics
and the study of population dynamics. Gradualism was once again the
dominant opinion, although it was somewhat modified in the 1970s.

It was at this point when Niles Eldredge
and Stephen Jay Gould put forward their theory of punctuated
equilibrium, which argued that evolution proceeds by bursts, followed
by long periods of stasis. Their arguments were based on observations
of the fossil record which seems to indicate that on the whole,
evolution proceeds in this uneven way. The bursts should not, however,
be understood as occurring in a few generations. Rather, these bursts
are only rapid when considered on geological time scales spanning
millions of years, and speciation events occur over thousands of
generations, making punctuated equilibrium a form of gradualism.

These three scientific ideas
subsumed within the notion of evolution do not contain any
materialistic or atheistic philosophy in themselves, which is the
fourth idea sometimes contained within the term evolution. This
atheistic notion, which I call evolutionism, is a philosophy that
claims that the material process of evolution dispenses with the need
for a creator. It argues that evolution demonstrates that humans are
not in any way special, that we are merely the products of a material
process, and therefore are fundamentally material in nature. The
science of evolution, according to this philosophy, has replaced the
need for a divine creator, and postulates that there is no necessity in
the emergence of humans. We would then be solely the products of
material forces, and are completely contingent on them. It is therefore
erroneous to believe that we somehow hold a necessary and central place
in the universe in which we live, or that, by implication, we exist by
the express will of a creator.

There are, of course, many people, among
them prominent scientists, who have claimed and continue to claim that
the scientific notions of evolution do indeed necessarily imply such a
materialistic philosophy. Richard Dawkins is among the most vocal
proponents of such a philosophy, arguing that "Darwin made it possible
to be an intellectually fulfilled atheist". This strident atheism does
not, however, help their scientific work in any way, and on the
contrary, is the source of so much of the controversy that rages over
it.

It is a fundamental mistake, however, to
accept their bundling of the three scientific evolutionary ideas with
what I have termed evolutionism. Rather, a more sophisticated response
would be to show that the three scientific notions in any form are
compatible with theistic philosophy.

In many cases, however, the reaction of
religious believers to the materialistic claims of evolutionism is not
to simply reject the assertion that evolutionism necessarily follows
from scientific ideas. Rather, they tacitly or unconsciously accept the
bundling of evolutionism with the science, and then see no option but
to attack a part or all of the scientific ideas of evolution as a way
of cutting the support for the philosophical claims of evolutionism.

In doing so, however, they find themselves
in the awkward situation of attacking a solidly established science,
ultimately motivated not by objections to the science per se, but by the illicit bundling of evolutionism with the science.

Young earth creationists are the first and
crudest variant of this reaction, but they are by no means the only
one. The Intelligent Design (ID) movement accepts common descent to
varying degrees, but rejects the established mechanisms of evolutionary
change. The arguments of ID proponents are structured in the way I have
outlined. Reacting to evolutionism, they have chosen to go on the
attack against natural selection and genetic drift. They recognize that
common descent is evident and they accept it.

It is clear, however, that their
motivations are at least partially to recreate a place for God in a
science of evolution. This is an effort that I believe is futile, and
has been adequately refuted. We must bring God into evolution not on
the order of material causality, as ID hopes to do, but on a
philosophical level. It is to this question that I now turn.

Philosophical resistance to evolution

How can theistic philosophy and
evolution taken in its established scientific sense be reconciled? Or
are those who bundle evolutionism with the science correct? It is in
fact many religiously-minded people who argue that it is not possible
to effect such a reconciliation, and put forward philosophical
arguments against it. I believe that such a reconciliation is indeed
possible, and that there are six key philosophical points that need to
be considered for this reconciliation to take place. These are:
contingency, final causality, divine providence, primary and secondary
causality, and order. What I present here is the bare outline of what
such a reconciliation could look like, recognizing that its brevity
cannot do it full justice.

Contingency

One concern that
religious people have regarding evolution is that somehow, it makes us
simply into products of chance, or more specifically, that evolution
shows that our existence is dependent on events that could very easily
not have happened. An asteroid striking the earth and wiping out the
dinosaurs so many million years ago is just the most dramatic of such
contingent events which influenced the evolutionary history of life on
earth that ultimately produced us. There are uncountable other events
that, had some conditions been slightly different, we would simply not
be here.

This question of randomness and historical contingency, which has
frequently been the subject of debate in the context of a theistic
approach to evolution, touches on this point. If the processes which at
least in part drive evolutionary change are random, does this not
remove any possibility that humans are the product of a divine will?

An evolutionary demonstration of the radical contingency of our
existence is not, however, problematic from a theistic point of view.
On the contrary, in traditional Christian philosophy, the entire
universe, including man, has been seen as philosophically contingent,
meaning that it is possible that it not exist. There is only one
necessary being, and that is God. In this sense, any scientific
demonstration of the radically contingent nature of our existence can
be seen as a scientific proof of a concept that has long been part of
Christian philosophy: it is or was possible that we not be. There is
then no need to resist the contingency that evolution demonstrates.

There are some who have argued that the chance element of evolution
is somehow atheistic by its very nature. While it is certainly possible
to claim that the randomness of events in the evolutionary history of
life on earth lies outside of divine providence or excludes the
possibility of providence, this is not part of the science of
evolution, being a claim that is of its very nature a philosophical
one. The mathematics of randomness in evolutionary biology is no
different than that found in so many other sciences, such as quantum
mechanics or gas dynamics. If evolutionary science is atheistic because
it makes use of statistics, than so is much of the rest of modern
science.

It is, however, a mistake to think that divine providence functions
always through necessary causes, as most of the time it functions
through contingent ones. One further problem with the view that the
scientific randomness of evolution entails atheism is that it implies
that the action of divine providence is somehow detectable by
statistical analyses. This, however, is problematic, not the least
because no one claims that the current state of our statistics as
applied in the sciences completely describes all causality in the
material world, let alone detecting the action of divine providence.

Final causality

Final causality has
lurked behind many of the arguments against evolution coming from
religious believers. William Paley made famous the watchmaker argument,
which is the best-known form of an argument based on final causes.
Paley in fact borrowed the argument from the Dutch philosopher Bernard
Nieuwentyt, and it has been rehashed in many forms since, most recently
by proponent of ID with their argument from irreducible complexity.

The basic form of the argument from final causes runs like this:
since complex biological systems are composed of different parts coming
together for specific purposes, and since such a construction of parts
can only be the product of a mind designing this system to meet a
particular purpose, then a complex biological system, like any system
where parts come together for specific ends, must be the product of a
willful and intelligent designer. Biological systems, and hence living
beings, cannot therefore be the product of any process that does not
originate from a willful and intelligent agent having a specific end in
view. Any claim that evolution as a material process is a cause of the
finality of biological systems is therefore incorrect.

The irreducible complexity argument goes further and claims that
since parts of micro-biological systems serve no function except as in
a complete system, they cannot have evolved gradually, as a half-formed
system is useless and cannot be acted upon by selection. Therefore the
whole system must be the product of an intelligent designer.

The flaw in the argument from final causes lies in the second
premise: that final causality is always the product of a willful and
intelligent designer. The key point is to recognize that it is an
undemonstrated assumption that every system in which some form of final
causality is present must necessarily be an object constructed by a
willful and intelligent agent.

This, however, is an invalid assumption because it makes no
distinction between the type of final causality found in biological
systems and that found in human-made artefacts. Anything made by human
hands has an external or extrinsic final causality: it is made to serve
a purpose external to itself, such as a chair for sitting on.
Biological systems, however, typically exist for an internal or
intrinsic purpose: they help the creature which possesses the systems
in question to survive and thrive in some way. For example, horses have not
evolved saddles.

Having made a distinction between the kinds of final causality, it
is also possible to accept that they can have different sources.
Evolutionary theory, and natural selection in particular, is a
demonstration that the internal final causality of biological systems
does not have an intelligent and willful agent as their source. There
is, furthermore, significant evidence that biological systems are
co-opted to perform different functions than they originally evolved to
fill, often losing parts in the process, and that therefore the
internal final causality of biological system changes as evolution
proceeds. A clear case of this is limbs. Their uses vary from wings for
flying and swimming among the birds, to grasping among primates, and
walking in many species. Such change in function also occurs on smaller
scales as well, such as with the components of the flagellum, which are
homologous with toxin injection systems in some bacteria.

A further problem with an argument from final causes is that it
assumes that the system in its current form is a reflection of its
evolutionary history. That is, it assumes that the biological system
has been built like a watch, with the designer putting together the
final product from parts based on a blueprint. As the changing use of
systems demonstrates, however, biological systems are not watches built
from scratch for a single purpose. Their uses change with evolution,
and as this happens, newly useless parts disappear, and the current
form of new systems no longer reflect their evolutionary history.

There is a somewhat different, less mechanistic, and more
philosophical form of the argument from final causes. Based on
Aristotelian philosophy, it is sometimes argued that evolution as a
material process cannot be the cause of the capabilities or potencies
found in living beings. Animals have greater capabilities than plants
because they have senses and are able to know things. Plants lack these
powers, but are able to reproduce and grow, unlike the non-living
world. Greater capabilities, however, cannot be given by an agent or
force that does not already possess those same capabilities, and
evolution as a purely material and non-living process cannot be the
cause of life, of growth, of sensory awareness and of the mental
faculties of animals. One needs a cause that is somehow proportional to
its effects, and evolution, as a material force, is not proportional to
the effects it supposedly brings about.

As with the argument based on final causes, the flaw here lies in
the assumption that evolution, as a material force lacking the
capabilities it confers on animals, cannot be the cause of these
powers. If one strictly holds to this assumption, then evolution is an a priori impossibility, no matter what science may tell us. This, however, is a
dangerous situation to be in, especially as the source of this
assumption is the Aristotelian philosophy that has been modified many
times in the face of the growth of scientific knowledge. This
philosophy held the perfection of the heavenly spheres, the
immovability of the earth, and the existence of the four fundamental
elements of fire, air, earth, and water. These ideas and more were set
aside in the face of scientific evidence to the contrary coming from
astronomy, physics, and chemistry. Likewise, the science of
evolutionary biology demonstrates that it is possible to acquire these
capabilities by the ordering forces at work in evolution. The study of
emerging complexity is an important and growing element of how such
highly ordered systems can emerged through the action of evolutionary
forces, although much work still needs to be done.

Providence

Does evolution do away
with the continuing action of God in creation? If evolution is a
sufficient cause to explain life on earth, at least in its material
form (ie, excluding the human soul), then have we banished God from
creation, like the deists of the 18th century did? Is there any room
for divine providence in an evolutionary view, which excludes a willful
designer on the material order?

Traditionally, a distinction has been made between extraordinary and
ordinary divine providence. Extraordinary providence is a miraculous
intervention of God, whereby the ordinary proceedings of the universe
are suspended by a direct divine intervention in the world. The
ordinary providence of God, however, is his will acting in the world
through the causality inherent to this world, and completely according
to its nature.

Because of this, it is totally hidden in any local sense, meaning
that no scientific experiment can discover the ordinary providence of
God. Our own human experience of the action of God in this world is
through this ordinary providence. Very rare are people who claim to
experience miracles, but surely believers do not deny divine action in
our lives because we do not have much experience with the extraordinary
providence of God. Indeed, for most people, God must be found in his
ordinary providence, and seeking him elsewhere will inevitably result
in disappointment.

In addition, the ordinary providence of God is no less wonderful and
beautiful than his extraordinary providence, and in many ways
evolution, as part of the ordinary providence of God, demonstrates
this. We can be in awe of the beauty of the living world in its micro
and macro scales, without having to claim that they are products of the
extraordinary providence of God. Indeed, it increases the awe believers
can feel when confronted with biological systems if we can understand
them as products of the ordinary providence of God acting through
evolution.

Primary and secondary causality

If evolution is a
sufficient explanation for life on earth, does this mean that there is
no place for God in this process? This exclusion is valid only if we
understand God as a secondary cause. A problem with seeing God as
functioning in an anthropomorphized way to create biological systems
and species by miracles is that it reduces his creative action to
functioning on the order of secondary causality.

As I have discussed above, God in general does not function through
his extraordinary providence, as our own experience suggests. Rather,
he respects the nature of his creation and allows it to function
according to that nature. His action in the world is not, however,
excluded because of this respect he has for his creation. Rather, he is
able to function through the nature of his creation, and he raises its
dignity by having it participate in his will according to its nature,
as he does in our own lives. God wants to act through us, without
removing the dignity we derive from being real causes. He wants to act
through us precisely so that we can have the dignity of being real
causes.

When God functions in this way, working through and respecting the
nature of the universe he has created, he functions as the ultimate
cause of things by holding them in being and guiding the course of
events according to his ordinary providence. Trying to make God into a
secondary cause, whereby he sets aside the laws of the universe to
create the first flagellum or ostrich is fraught with difficulty, both
scientifically and philosophically.

On one hand, there is the God of the gaps problem: one’s belief in
God is threatened when an "ordinary" secondary cause is found to
explain a problem that God was being made use of to explain. On the
other, there is the problem of trying to explain why God is such a
strange designer: he seems to act as if he is a material biological
process, leaving behind a messy trail of vestigial organs,
inefficiency, brutality and disease. When God is understood as the
primary cause of being, these problems disappear, or at least move to a
different order. We do not need to ascribe the limitations of evolution
to God, just as we do not need to ascribe human limitation to God, even
though he wants to use us as his instruments.

Order

Another frequently
proposed philosophical argument against evolution is based on order.
The argument has many forms, but basically it proceeds from the highly
ordered nature of biological systems. They are very complex, and
function very well under many different environmental conditions. They
are so highly ordered that science is continually exposing further
levels of complexity in their functioning. If we cannot yet even
approach creating systems of such complexity and order, then surely it
is foolishness to believe that such systems are the product of the
material forces of evolution. Many times, it is claimed that this
argument is exactly what Thomas Aquinas was arguing in his fifth proof
for the existence of God.

The order of the universe is certainly a way of appreciating the
existence of God, but this order cannot be reduced to something that a
created intelligence could be the cause of, because if it were, then
this order would not be the proof for the existence of God, but rather
an anthropomorphized version of him. A biological system, if looked at
only as a final product, can indeed be the product of a created
intellect, as the ID proponent who allow that an alien could be the
designer recognize, and hence does not prove the existence of God.

By contrast, a complex biological system which is seen as the
product of the natural laws of the universe cannot be reduced to a
product of a created intellect. A created agent has no power to both
create and maintain the laws of the universe such that these laws
produce living beings. Only God does. Hence, looking at highly ordered
biological systems as products of natural forces can be viewed as a
proof for the existence of God. Removing the natural forces from this
vision of order, however, deprives the argument of the strength needed
to make it a proof for the existence of God, and makes it merely an
argument for an intelligent designer or an anthropomorphized deity, and
a weak argument at that.

At the end this year celebrating Darwin’s work, it is
regrettable that there still exists some tension between religion and
evolutionary science, even if it does not stem so much from official
doctrines as from the feelings of believers. Some of this tension is
inevitable given the atheistic claims of evolutionism, but there are
ways to reconcile evolutionary science with theistic philosophy, as
many people have done, and as I have outlined here.

The science of evolutionary biology is very well established, and
the residual tension between religion and evolutionary biology harms
both. On one hand, it makes the scientific work evolutionary biologists
suspect in the eyes of many, and on the other, it makes religion appear
like a regressive force. It is far better to reject the bundling of
evolutionary biology with evolutionism, the real crux of the problem,
than to wage a war over the minutiae of evolutionary biology, which
should not be problematic from a religious point of view. Finally,
accepting theistic evolution does not diminish the beauty and awe we
can feel when contemplating God’s creation. On the contrary, God’s is
manifest in his works, including in evolution.