Cross-post: what is science?

The following are reflections based on my years teaching introductory astronomy for non-science majors.  Few of my students take the class out of personal interest.  It fulfills a natural sciences general education requirement and sounds less scary than geology or chemistry.  Thus, the ultimate purpose of the class is to expose students to the scientific enterprise, so I put a lot of thought into the impression of science I’m giving them.  When I speak of “science” below, I will be using the word in its modern rather than its classical sense, according to which biology and sociology are sciences while philosophy and history are not.

Survey course textbooks in the branches of science usually include some discussion of the general nature of science.  Anxious to emphasize science’s quality as a process rather than a fixed body of knowledge, they often hold up the “scientific method” as the essence of science.  This, however, has disadvantages.  For one, actual science rarely follows the model given in these books.  More importantly, the scientific method is itself given no real justification, and the limits of its usefulness are left unclear.  What makes this problem pressing is that students may believe, and textbooks may even state, that the scientific method involves assumptions about the world and excludes a priori certain kinds of explanation, as for instance when scientific explanations are contrasted with assertions of miraculous or animistic spiritual causality.  The impression is given that science is at least methodologically naturalist, that when thinking scientifically we must pretend to be atheists.  This, I emphasize, is not a problem for religion; it’s a problem for science.  To tie oneself from the beginning to very questionable metaphysical assumptions threatens the credibility of the whole enterprise.

The subject matter of science

The alternative is to define science according to its subject matter and to derive the scientific method from that.  In this way, one can also show how certain things can be taken to fall outside the scientific purview without making questionable philosophical assumptions.  The subject matter of science, I would say, is the set of contingent patterns observed in the world.  That is, the key act of scientific intuition is to notice some regularity in the world that didn’t logically have to be there and yet is.  The first example I give my students is the motion of the stars in the night sky.  One can imagine all sorts of ways they might move, but in fact they all make circles around Polaris once per sidereal day.  Having noticed a pattern like this, one then goes on to posit an explanation, a reduction of the imaginable degrees of freedom of the world such that the observed pattern would have to happen.  For the night sky, one might postulate that the stars are all fixed onto a rotating celestial sphere, from which their common motion would follow.  Notice already that science makes no claim to explain everything about the world.  The celestial sphere model does not explain why the sphere’s spin period is what it is or why the stars are distributed about it as they are.  There are no discernible patterns here, so scientifically there is nothing to explain.  The general properties of spheres in Euclidean space also don’t count as science, although scientific explanations make use of them, because these properties are not contingent.  They are necessary, and therefore best studied by a discipline of pure reason, in this case mathematics.

There will often be more than one possible explanation for the observed facts.  For example, one can also explain the motion of the stars by assuming they are far enough away that their peculiar velocities are unobservable but that the Earth is spinning about an axis.  To decide which (if any) proposed explanation is true, one must then find some other set of observables for which the explanations make different predictions and see which (if any) is vindicated.  This is the core of the “scientific method”.  It is the logical way to proceed for the sort of questions science asks.

Does science assume (at least methodologically) that there is no God?

We can now see why God’s existence and actions are not matters of scientific reasoning.  God’s existence is not amenable to the scientific method because it is necessary, not contingent.  Ask a theist what sort of universe would have God as its Creator (thinking to then go do an investigation to see if our universe resembles it), and he will say “any sort of universe”.  An atheist who understands the issue (that if a necessary being is coherent and thus can exist, itmust exist) would say “no sort of universe”, that the idea of God is nonsensical.  Either way, the methods used to discern contingent truths are not useful.

When one says that science does not accept miracles, one usually means acts of God that don’t follow general rules.  It is in fact the lack of pattern to miracles–the fact that God does not oblige Himself to perform them every time some set of conditions is satisfied–rather than their divine cause that makes them unfit for scientific study.  If one is an occasionalist and believes that every act is performed directly by God, but that He usually binds Himself to acting in regular ways, then these regularities can be analyzed scientifically like any other patterns.  (In fact, the occasionalist will deny that there are other patterns.)

Scientific reductionism

The general public’s impression of science is tied up with what is thought of as a distinctly scientific worldview.  According to this worldview, intelligibility proceeds from the bottom up.  Wholes are understood by enumerating their parts, rather than understanding parts via their relationship to the whole.  At the basic level are fundamental forces like gravity understood as a sort of insatiable striving, while the settled structures of the world are points of stable equilibrium between opposing forces.  This is an extremely powerful way of viewing the world, with many successes.  It wouldn’t be fair to say that it has been established as true, as if some alternative top-down set of theories had been ruled out by experiment.  It’s more true to say that these are the only type of truly predictive theories we know how to build.  Whether that says something about the world or about us I leave to philosophers.  In my classes, I put a huge emphasis on the ideas of equilibrium and stability, because I do think they capture some aspect of the truth about the physical world.

Of course, the romance of reductionism hasn’t stayed put in the physical sciences.  In the eighteenth century, we see it spreading to economics and politics.  An example would be the classical liberalism of America’s Founders, with its emphasis on checks and balances of power, as opposed to the Platonic-Ciceronian-Augustinian emphasis on ordering the whole toward the highest common good.  Many people feel alienated by an economic or political order that is merely emergent, that fails to address man at his moral center.  Both conservatism and Marxism appeal to this sense, and they are right to deny that society must be understood on a Newtonian model, whatever the structure of the physical world should happen to be.

The practice of science from a humanist perspective

Broadly speaking, one can identify two attitudes toward a discipline of knowledge, which I will call the scientific and the humanist.  Sciences are ordered toward the expansion of a body of knowledge.  Particular intellectual virtues must be imparted to those who would participate in  this process, but the accumulation of knowledge, rather than the habits of mind that foster it, must be the organizing principle.  Humanities, on the other hand, are primarily ordered to the refinement of those who study them.  They are not, and should not be, progressive in the way sciences naturally are.  Thus, philosophy is a humanity in this way of speaking, because, although there is knowledge to be had from philosophy, it is not detachable from the process of its elucidation in the way results of physics and mathematics are.  A person embarking on the study of philosophy may ask a question like “Does free will exist?”, and by the end of his study he may have an answer, but that answer could not have been handed to him before his study, because his understanding of “free will” will have been transformed by philosophizing.  In contrast, anybody can understand what Fermat’s Last Theorem states, although few could follow the proof.

Requiring non-science majors to take a science class means treating science in a humanist way.  I am not being asked to incorporate them into the process of scientific research.  That’s not really feasible for anyone below the upper undergraduate level.  I’m being asked to expose them to a particular way of thinking, to help them develop a scientific “sensibility” in the way that a survey class on literature might be expected to foster an appreciation for literature.

The usual claim is that we teach students a kind of problem solving skill, “scientific” or “quantitative” reasoning, which is one of the many species of the “critical thinking” that universities exist to foster.  Certainly I do force students to follow some pieces of scientific reasoning, mostly having to do with how properties of stars are inferred, to give them the flavor of it.  However, I don’t think it’s realistic to expect a survey class to turn students into scientific problem solvers.  It’s a well known observation that physics majors themselves don’t start thinking like scientists until they get deep into research.

I do hope to stimulate in them, at least a bit, a “scientific sense” of noticing contingent patterns in the world.  Simply noticing a regularity about the world, not taking it for granted but asking why it should be as it is, is a great achievement.  Sometimes the implications of an everyday fact are profound, an example being how we now regard the fact that the sky is dark at night as evidence that the universe is not static and infinitely old.  It’s exhilarating to think that other great clues about the cosmos might still be staring us in the face, waiting for us to notice.  Even if one just shrugs and says “I’m sure there’s some explanation for that”, this sort of noticing is a distinct way of appreciating the world, complimentary to the aesthetic sense fostered by a regular humanities class.