Galileo is probably best known for his work The Dialogue on the Two Chief World Systems, the book that triggered his ill-fated encounter with the Inquisition. However, when it comes to Galileo’s role in shaping our understanding of the modern scientific enterprise, it is his 1623 work The Assayer that has had a much larger impact. In one of the most quoted lines in the book, Galileo sums up his view of science, a view that has come to dominate our understanding of science ever since:
Philosophy is written in this grand book the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and to read the alphabet in which it is composed. It is written in the language of mathematics, and its characters are triangles, circles, and other geometric figures, without which it is humanly impossible to understand a single word of it; without these, one wanders about in a dark labyrinth.
Galileo saw, clearer than most, the uncanny ability of mathematics to describe the world around us. In Galileo’s mind, if one really wanted to understand the material world, one must measure it and describe it mathematically. Orbits could be reduced to mathematical figures and mathematical equations. Likewise, the trajectory of a cannonball or the acceleration of a falling object could be described mathematically with staggering precision.
The ability to measure and quantify, to reduce entities like electric currents to equations has without doubt deepened our understandings of the natural world. It has given us an appreciation for the workings of selective pressures in evolution, the relationship between energy and matter, and the interactions between some of the most fundamental forces in physics. In addition, it has fueled the development of everything from microwaves to rockets to iPhones.
Yet, as we bask in our significant scientific and technological successes, it is easy to lose our perspective. Too often we slip into the assumption that because we can describe an entity or behavior mathematically, that we therefore understand it. Take gravity for example. While we can measure it and define equations relating gravity to the mass of objects and their distance, we do not know what it is in any fundamental sense. While we know how it affects objects, at a certain level it remains a mystery. This is true of many other phenomena such as the wave/particle duality of light, the origin of the first cell, and quantum entanglement. While these can be modeled to some extent, and in some cases be described mathematically, wrapping the human mind around the reality of such concepts is another activity altogether. As Richard Feynman once said, “I think I can safely say that nobody understands quantum mechanics.”
This distinction between factual knowledge and understanding lies at the heart of a popular misconception of what science is and what it can provide. Students often have the impression that what separates the sciences from the humanities is that the sciences are fact-based, that there are right and wrong answers while the humanities are speculative. Nothing could be further from the truth. While science explores the natural world and has been able to generate an impressive array of factual knowledge, all disciplines are fact laden. Just ask an undergrad struggling to recall the dates of Church councils in a theology class or the names of the Existentialists in a philosophy class. Facts are essential for any discipline and science is no exception. Yet, any science that does not go beyond facts is not fit to be called scientific.
Science is more than measuring the world in the manner Galileo described. At its core, it is an attempt to use those measurements, use those facts, to construct theoretical and conceptual frameworks that can broaden our understanding of the natural world. For example, in evolutionary biology there exists an enormous catalogue of fossils that have been meticulously quantified over the years. However, they only contribute to our understanding when scientists either 1) integrate them into an existing theoretical framework or 2) use them to construct a novel theoretical framework. Absent this, they are quite simply a disjointed pile of bones and shells.
The data we accumulate, the measurements we attain, do not do dictate our theories. Building theories requires human ingenuity and insight that goes well beyond the facts of science. The reality is that multiple theories or explanations can be given to the same set of facts. The scientific enterprise consists of sorting through these explanations. Taxonomy is an excellent example of this. As pointed out by the historian of science Sandra Mitchell, “nature underdetermines taxonomy (i.e., there is more than one classification consistent with the results of empirical investigation), which classification we adopt must be chosen for reasons other than empirical ones. Species can be divvied up by a criterion of reproductive isolation or by genealogy, for example.” As a result, taxonomic disputes are a way of life in biology.
Likewise, when paleontologists classify fossils, the methods and weights they use to build their phylogenetic trees can influence the outcome of the process. The decisions about which method to use though is not dictated by the measurements. The fossils do not tell the researchers which one to apply, yet different methods give different trees. How then do we know which phylogenetic tree most accurately describes the evolutionary history? Getting more data, in this case more fossils, can help. However, the irony is that as we broaden our understanding with new knowledge, we find the world becoming more complex and inscrutable. New fossils often do not resolve two different trees but instead lead to additional phylogenetic possibilities that were not even thought of before. New data does not always resolve old problems, but it almost certainly will create new ones.
As a result, the questions we ask today, the scientific view of the world we hold today, is limited. It is only as good as our current understanding. This is the great lesson of the history of science. According to the philosopher of science Nicholas Rescher: “Most of the questions with which present-day science grapples could not even have been raised in the state-of-the-art that prevailed a generation ago.”
The history of cell biology over the last two-hundred years illustrates this well. In the mid nineteenth century, most biologists though that the cell was a simplistic sack of protoplasm, a homogenous viscous fluid that provided the basis for life. Techniques developed by scientists in the twentieth century, however, allowed us to peer into this protoplasm and shatter the simplistic notion of its homogeneity. The cell contained staggering amounts of nucleic acids, proteins, and lipids, all arranged in a highly organized manner to create the organelles and transport systems that sustained life. Yet, with this new knowledge of the “protoplasm,” the number of unanswered questions expanded exponentially. How did the cell maintain its structure? How did it regulate its organelles? How did its disparate parts communicate? How did the cell control the thousands of metabolites it produced and consumed?
Spurred on by a strong belief in genetic reductionism, many researchers thought that the advances in genome sequencing that occurred at the end of the twentieth century would help unlock these mysteries. But the sequencing data only brought more questions. In retrospect it seems obvious that genes would be just one piece of the puzzle. As the editor of one scientific journal cautioned at the time, “Everyone seems to have forgotten that every gene needs environmental causes to express itself. Hence studying genes is only as important as studying their external counterparts.” Genes are not autonomous. Rather they are largely controlled by complex global processes and pathways within the cell that are highly influenced by the environment.
This realization has spurred new questions regarding the epigenetic regulation and control of genes and new fields of study like systems biology that are asking questions that no mid-twentieth century cell biologists could have possibly formulated. In addition, systems biology has produced mounds of data regarding the complex interactions within the cell, data that will keep a generation of scientists busy deciphering, contextualizing, and theory building.
Despite all this data, despite all this progress, big questions remain. The biochemist Nicholas Wade sums up the current state of biology this way: “Some 350 years after the discovery of cells, we still don’t know why life on earth is the way it is . . . The biggest questions in biology are yet to be solved.” This situation is not unique to cell biology. Scientific discovery always opens up new frontiers, each question “answered,” spawns countless more questions, more avenues for investigation, and in some cases entirely new disciplines.
Furthermore, most scientific questions are never completely resolved and the really big scientific questions remain open to debate. They remain “underdetermined by the data.” Does the Copenhagen interpretation represent the correct understanding of quantum mechanics? Was the Cambrian explosion caused by an environmental trigger or was it fueled by a singularly rare transitional event amongst early metazoans? Which model best explains the rate at which the globe is actually warming? Yet, one could go even further as it is possible that the biggest questions have yet to be formulated. As Rescher points out: “Scientific inquiry is a creative process of theoretical and conceptual innovation; it is not a matter of pinpointing the most attractive alternative within the presently specifiable range, but one of enhancing and enlarging the range of envisageable alternatives.” New data, new advances can bring us new possibilities, new theories that are presently hidden from our view. We do not even know what we do not know. Physical reality is more complex that we can comprehend and our knowledge of its workings is more limited than we care to admit.
While this situation might seem daunting to a practicing scientist, it appears to speak to a fundamental truth about the nature of the physical world and our relationship to it. In the Catholic tradition, there are two great books by which the Creator reveals himself, the Book of Nature and the Book of Scripture. As we read the Book of Nature, we are meant to proclaim as the Psalmist does, “The heavens declare the glory of God.” There is an aspect of wonder that is inherent to scientific discovery and exploration that parallels the wonder we experience before God. But what else does the Book of Nature speak to us about? What else does modern science reveal to us about the mystery of God? Another clear message is that the human mind is well-suited to probe the secrets of his created world, of investigating its structure. In some sense, God desired that we enter the mystery of his Creation through the study of science. The language of mathematics, a human construct, has allowed us to gain insights into, amongst other things, the relationships between the fundamental forces within the natural world. On a fundamental level, our mind is equipped with the tools needed for scientific discovery.
Yet, before any hubris sets in, the Book of Nature also reveals that at the heart of Creation lies a mystery. While we can always penetrate further into this mystery using our human reason, we can never seem to exhaust it. All our measurements, all our mathematics, has yet to tame this mystery. Rather, each discovery, like a log tossed onto a fire, only serves to further fan its flames.
In this sense, our reading of the Book of Nature parallels the work of the theologian as he or she attempts to penetrate the mystery of God. Theologians can approach the Mystery, yet they know they will never exhaust it. As the Catechism states: “Since our knowledge of God is limited, our language about him is equally so. We can name God only . . . in accordance with our limited human ways of knowing and thinking.” In a similar fashion, modern science seems unable to fully exhaust its subject matter. Our mind is such that we can penetrate the order and rationality of Creation, but we seem to be unable to exhaust the mystery.
But should we expect anything less from science? As we read the Book of Nature, should we expect to come to an exhaustive understanding of his Creation? Or, much like one can plumb the depths of Sacred Scripture and continually find new meaning, wisdom, and insights, should the Book of Nature to be any different? Should we expect an end of science, a day when we have deciphered all there is to know about the physical world? Or are we as humans unable to fully penetrate the created world in much the same way that we will never be able to fully penetrate the mystery of God.
Certainly, there are historical and philosophical reasons for positing there will never be an end to science. As Rescher points out:
If the future is anything like the past, if historical experience affords any sort of guidance in these matters, then we know that all of our scientific theses and theories at the present scientific frontier will ultimately require revision in some (presently altogether indiscernible) details. All the experience we can muster indicates that there is no justification for viewing our science as more than an inherently imperfect stage within an ongoing development.
Yet, might there be theological reasons to suspect this as well? If the mystery of the created world is meant to reveal the mystery of its Author, then those looking for certainty in science should go elsewhere. Science is not about certainty and facts, it is about continually building and reshaping theories, it is about encountering a mystery. In this way, modern science has deep parallels with theology.
Too often though this parallel is lost on those who would flatten science into to a series of facts and proofs. Science is much more human than that, it is all at once tentative, probing, mysterious and majestic. Debates about the scientific theory of evolution illustrate this key point. The scientific theory of evolution is not a fact, it is incomplete and will remain so despite future discoveries. It is a mystery that we cannot fully penetrate. So are all scientific theories. Yet this does not mean we should discard evolutionary theories or attempt to construct biological theories of Intelligent Design any more so than we should discard the reality of a Trinitarian God given that our earthly understanding of the Trinity will always remain incomplete. It seems we will never exhaust the riches of the Created world, just as we as creatures can never fully comprehend the nature of God. But this does not leave us without hope. Just as we have analogies to understand the nature of the Trinity, we build theories to help shape our understanding of the facts of science. Yet, it is important to realize that neither the analogies nor the theories are exhaustive. The Catechism makes this point as well:
God transcends all creatures. We must therefore continually purify our language of everything in it that is limited, image-bound or imperfect, if we are not to confuse our image of God—“the inexpressible, the incomprehensible, the invisible, the ungraspable”—with our human representations. Our human words always fall short of the mystery of God.
Though we fall short, God still desires that we understand him and his Creation, the work of his hands. Human reason has equipped us to do so. Yet, even with the best of human tools and the most prepared of human minds, the scientific enterprise, our great effort to read the Book of Nature, remains incomplete. While portions of the truth become accessible to us, other aspects seem to remain beyond our grasp. The Book of Nature, while written in the language of mathematics, does not end in a neat and tidy batch of formulas, angles, weights, and measures but rather points beyond itself. It reveals a God that is not only wonder and beauty, but who is infinite and inexhaustible. Scientific discovery draws us into precisely that mystery, the inexhaustible mystery of the Created world, a world that reflects our infinite Creator.
