Five Things Science Cannot Prove (that are necessary to do science)

Perhaps the most common misunderstanding of science today is the idea that it alone operates only on what can be proven.  The scientist, we are told, unlike the historian, sociologist, or (shudder) the theologian, believes nothing except what is proven to be true by the scientific method; therefore he or she alone is the oracle of true knowledge of the physical world.

It is remarkable how prevalent this thought is, even when not articulated, since it is so easily shown to be not the case.  Science is a wonderful and noble way of exploring and understanding this world we find ourselves in, but it in no way operates solely on the basis of proof. Some things it must assume. I will list a few of them.

[Note: nothing I can say will stop some people from viewing this as an attack on science; it is anything but, as I think any reasonable reading will show. ]

  1. 1. Reality is rational.

That is, its makeup is such that it exhibits order and consistency, so that we can make predictions and postulate laws and theories.  Now this may seem like common sense, but that would be common only to sensibilities formed in and shaped by what could loosely be defined as “western” thought (though of course we mean history more than geography here).  To the ancients, and to many of the east today, the idea that the universe is rational and subject completely in its physical workings to consistency and order is not something assumed at all.

Nor can reality be “proven” to be rational.  Indeed, ask yourself how this would be proven from the viewpoint of someone within this reality.  You cannot prove it by experiment, for you cannot experiment on reality as a whole. You cannot prove it by induction, arguing that since everything we have studied has proven rational that reality itself must be. An inductive argument like this fails for four reasons.  First, an inductive argument of this sort will only grant a probable truth, not a certain one, so the best we could say is that, “reality is probably rational” which is a world different from saying “reality is rational”. Second, we have no way of measuring how much of reality we have “figured out” versus how much we have not, so there is no way of knowing if we have high probability or very low probability for our inductive claim.  Thirdly, it is simply not the case that we have figured out everything we have been able to study.  When Richard Fenyman wrote, ‘I think I can safely say that nobody understands quantum mechanics,’ he was including himself which is disconcerting given how many books he wrote on that very subject.  No-one today can give a satisfactory answer to the most basic question of physics (how quantum mechanics and the theory of relativity can both be true since they contradict each other) nor can astronomers and astrophysicists give an agreed upon answer to the quandary that most of the matter of the universe (dark matter and dark energy) cannot even be observed (but must be assumed to make sense of everything else).  Fourth, even if everything we can study shows rationality, that is no proof that we do not inhabit a slice or bubble of the universe that has qualities different than the universe as a whole (an idea which some astrophysicists argue as possible).

Now, I do believe reality is rational, for I believe it is the creation of a rational being.  And I suspect the legacy of this belief gives a clue to why science developed more successfully in theistic societies than pagan, pantheistic or animistic ones.  So I am not arguing that reality is not rational, but that science is logically dependent on a belief that it cannot prove.  Unless reality is rational, science is not possible.

  1. 2. Reality is knowable.

This is not the same argument as above.  The success of the scientific method assumes not only that reality has the quality of rationality, but that it is also knowable. That is, it is conceivable that realist is rational, but I could be irrational, and not able to form valid conclusions about reality.  My mind must be “on the same wavelength” to capture its rationality.

Steven Pinker, the famous evolutionary biologist, unwittingly encounters this very issue when he writes on page 561 of “How the Mind Works”:

We are organisms, not angels, and our minds are organs, not pipelines to the truth. Our minds evolved by natural selection to solve problems that were life-and-death matters to our ancestors, not to commune with correctness or to answer any question we are capable of asking.

Somehow, one gets the impression that Pinker feels his own mind is an exception to this rule, else why would he write the book (or even ask us to believe the above quote).

But indeed, how could we prove that the human mind is a capable tool for understanding reality and finding truth, especially on the assumptions Pinker makes (that the mind evolved to solve practical problems that affect reproductive success, not to find truth)?  But without the belief that the human mind can understand reality, there is no reason to study reality.  One is better off not wasting the time.

Again, I am not arguing that reality is not knowable.  I believe it is because I believe the same rational being who created reality (thus ensuring its rationality) also created mankind in His own image, thus ensuring the possibility of valid knowledge of, and reasoning about, that reality. No, I cannot prove that scientifically.  But neither can the scientist prove that his or her mind is capable of anything more than an utilitarian problem solving that may or may not speak actual truth.

  1. 3. The uniformity of nature across time and space

Quick, what is the speed of light?  299 792 458 meters per second, of course.   But what was speed of light a second after the big bang? Or 4 billion years ago?  Or what will it be 4 billion years from now (or even next week?)  Of course we don’t know, in one sense. No-one measured the speed of light 4 billion years ago, and any knowledge of the measuring of the speed of light in the future is inaccessible to us.  Nor can we measure the speed of light right now except in that small sliver of the universe we can actually observe.  And the same is true of other laws of nature: gravity, the interplay of the parts of the atom, etc…

It should be noted here that the speed of light, for example, is derived from observation.  Every time we observe it, it is always that speed (or its speed makes possible other equations that correspond to present reality). But nothing in the nature of reality mandates that it must be at that speed; other speeds for light are at least conceivable.

So how do we know that the speed of light or other laws of physics apply across the universe (when we’ve only studied a sliver) and across time (when we only have access to the present?).  Technically, we do not know.  We assume.  Since all the places and times we have been able to observe follow these laws, it seems logical to assume that is also the case for the places and times we cannot observe.  But notice, this is an inductive argument, and as such can only give a probable conclusion, not an air-tight certainty.  Yet every science, if you dig deep enough, operates on the assumption of continuity and uniformity.  This is no mark against science; it can hardly do otherwise.  But it is still worth noting that the foundation is an assumed deduction, not a proven fact.

  1. 4. Causation

Surely, if there is one thing science can prove, it is that one thing causes another, right?  Actually, nothing could be farther from the case.  The very idea of causation must be assumed.

David Hume, of course, is the one who most famously has shown this.  Imagine, he said, I have one hundred windows in a row, and I take a hammer and hit the first 99.  All of them shatter.  I approach the last one.  Will it shatter also when I hit it?  Hume argues that you cannot know that, for there is no way of proving that the impact of the hammer caused the other windows to break. It is conceivable (even if unlikely) that some other forces or forces broke the windows at the exact time the hammer hit them.  Causation, he argued, is an attribute of the mind, by which it tries to make sense what happens in the world.  But there is no way to prove beyond doubt that causality applies beyond the mind’s interpretation.

Hume’s argument is epistemological, that is, a question of how we know things.  But 20th century science (in the form of quantum mechanics) itself has undermined the concept of causation (please read up on simultaneous causation and the uncertainty principle to see this).

Also, as I am writing this, the world of science has been shocked by the apparent find of a team at the European Center for Nuclear Research (CERN) that some particles travel faster than the speed of light. One article notes,

The existence of faster-than-light particles would wreak havoc on scientific theories of cause and effect.

“If things travel faster than the speed of light, A can cause B, [but] B can also cause A,” Parke [head of the theoretical physics department at the U.S. government-run Fermilab near Chicago, Illinois] said.

“If that happens, the concept of causality becomes ambiguous, and that would cause a great deal of trouble.”

At this point, both philosophically and scientifically, the simple idea of causation (A causes B) is very much a working assumption that makes science possible, not the result of science itself.  [Please note I am talking about the concept of causation, not examples of one thing causing another].

  1. 5. The very existence of an external universe consisting of matter

I will spend the least time here, for this is unable to be proven by any worldview or any method of knowledge.  Suffice it to say that both solipsism and idealism would deny the existence of an externally existing material universe.   Solipsism argues this world does not exist outside my mental projections, or, as my epistemology professor put it, “I’m the only pebble on the beach. And there is no beach”. Idealism argues that only the spiritual is real, and the material world is an illusion (or, as for Berkeley, real only as the thoughts of God).  Technically, neither idea is refutable (any arguments against them must come from inside the projection or illusion).

Again, this does not count in any way against science.  Of all the five things on this list, this is to me the least substantial (since no-one can consistently live out this idea).  I include it here to remind us of the need for intellectual humility, whether we are a scientist or theologian.

Other presuppositions of science include the following:

  • The laws of logic (especially the law of non-contradiction)
  • The adequacy of language to communicate reality and truth
  • The existence of numbers

All these have been argued by philosophers and others, and none of them can be proven by the scientific method.  In short, they are metaphysical assumptions, not proven facts.

Also, related to this but somewhat a distinct issue is that science assumes certain values in order to proceed, without being able to scientifically prove the validity of these values.  Chief among these values is that of honesty.

All this to say that science is a wonderful tool for granting knowledge about this universe we find ourselves in.  It in no way is to be despised or denigrated.  But enough of the foolish talk that it alone traffics in certainty and what is beyond doubt.  It is an invaluable servant, but makes a terrible idol.

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