One of the points that creationist Ken Ham made in his debate with Bill Nye, and presumably is still making on his site "Answers in Genesis," is that we have to distinguish between experimental and historical sciences. According to his argument, physics is an experimental science, evolution and geology are historical. Since the first type produces testable knowledge, and the second doesn’t, we can safely disregard the second and substitute Creationism in its place, without doing any damage to the first. I suppose a lot of people are inclined to dismiss this point as just obviously fatuous because Ken Ham made it, and because he’s attacking science, and therefore has to be resisted on all fronts. The instinct is sound, but as a strict matter of logic it doesn’t follow, and it’s not really rational to lurch to one extreme simply because one’s opponents have taken up residence on the other.
Maybe there’s an opportunity to learn about science here, so I’d like to take up Ken Ham’s point. He’s right that there is a distinction to be drawn, although he’s wrong to conclude, on that basis, that the results of the historical sciences can be disregarded at will. More on this later. The main difference between the experimental and the historical sciences is that the former are concerned with the elucidation of regularities across all events but specific to none of them, while the latter are concerned with the elucidation of specific, unique, non-repeatable events.
To take a familiar example, suppose that you wanted to study the trajectory of artillery shells. And suppose, further, that you didn’t know the specific equations that govern their flight, but had to rediscover them. A sensible way to go about this would be to set up an artillery piece, fire it a hundred or a thousand times (preferably under tightly controlled circumstances), and record the results. That is, you would conduct an experiment. The goal of the experiment would not be to describe the trajectory of any one shell, but rather of all the shells, and on that basis to isolate the underlying regularity, which might be called a “law” or a “physical constant.” Once you had isolated this, you could go on to make predictions about shells fired under less tightly controlled circumstances, and under those circumstances (say, a misfire, or a strong breeze) the behavior of the particular shells would change. The underlying regularity, however, would not.
Thus a “law of nature,” usually describable through an equation, does not refer to what must happen in any one particular case, but rather to a statistical regularity that pertains, we believe, across all cases. We can never be completely certain that we've got the statistical relationship right because we can’t observe all instances of the given phenomenon—we can observe many, and we can make reasonable inferences on that basis, but the universe is very large and very old and we only have significant experience of a very tiny corner of it, and over a very short period. Who knows, maybe the constants will change tomorrow. It’s not likely, but it’s at least conceivable (the question of how we know that physical constants do not change is a special case of a broader problem in philosophy, the problem of induction. For more on this, see Russell’s Chicken or Nelson Goodman’s concept of “Grue.”)
Suppose, however, that you had a different question in mind. Imagine that in the course of your experiments one of the shells misfired, the artillery piece exploded, and your ballistics lab burned to the ground. You might, naturally, be curious about the reason for this, and decide to conduct an investigation. Supposing that you had vast time and resources at your disposal, it would be possible to repeat the earlier, experimental approach, i.e. to build thousands of ballistics labs and fire tens of thousands of artillery pieces hundreds of thousands of times, all under tightly controlled circumstances, wait for some of them to burn down, look for statistical correlations, and then try to discover the underlying law that governs the burning down of ballistic laboratories.
Obviously, this wouldn’t be a very practical approach, but more to the point, it wouldn’t actually answer your question, which was not “Why do ballistics labs burn to the ground?” but why did your ballistic lab burn to the ground. It might be helpful to know what the underlying statistical regularity is—that, for instance 21% of burned-down laboratories are the result of an improperly installed fire-suppression system, 16% of faulty lab equipment, 11% of operator error, and so on, and that might point you in a useful direction—but it still wouldn’t tell you which of those factors was relevant to the destruction of your particular lab. What you would need to do is pick over the debris (the way they do when an airliner crashes), consult cell-phone records (if they're available), talk to the survivors (if there were any), and so on.
But no matter how thorough your investigation, you could never be entirely certain that you had got to the bottom of things. If you discovered, for instance, that the lab assistant was inexperienced, had been struggling with alcohol addiction, and was upset over a fight with his girlfriend, you might suspect that operator error played a role in the demise of your laboratory. But this would really only be circumstantial evidence. It’s also possible that, though inexperienced and struggling with difficult circumstances, your assistant had performed his tasks correctly, and that the problem was actually a poorly manufactured shell, a gas leak, or something else. Again, it would be a case of drawing inferences, and this would necessarily be somewhat indirect, because the particular event of your lab burning down on that particular day will never recur, and therefore cannot be directly observed. It is forever in the past, where we cannot go.
None of this is to say that experiments can tell us nothing about past events, or that particular events are irrelevant to establishing law-like regularities. As we have seen, even absurd experiments would have some value in the case of burning laboratories, and an experiment just is a collection of particular events. We can’t insist on an absolute distinction in this area any more than we can with the ship of Theseus. Rather, it’s a matter of emphasis, of choosing the best method for the best task.
Nevertheless, the person who insists that the experimental method is very sound and ought to be applied where possible certainly has a point. The precision of physics is largely due to the power of its methodology, and no doubt many researchers wish they had something of equal power at their disposal, even if there are reasons why experimentation in particular is not adequate. In this respect the results of the historical sciences are generally less certain than those of the experimental. The reason is that a law is a sort of if-then statement, of the form “under conditions X, the likely result will be Y.”
Thus a ballistics expert can tell you what will likely happen if you fire a shell at such and such an angle and velocity under such and such conditions, but not that you have fired it, or will fire it. The law is constant, but the event is contingent. In the same way, when discussing particular events, the question of whether those events actually occurred is distinct from the question of what laws would have governed them if they had. If knowledge of the trajectory of one artillery shell was all you had, you would never be able to deduce the underlying regularity that had governed its flight, nor, knowing only that regularity, would you be able to say whether a shell had been fired at a particular time and place. Rather, we derive our knowledge of the regularity from many repetitions of similar instances, and it is because we can repeat them so frequently and under so many different circumstances that we can have a high degree of confidence in the abstractions we arrive at in this way.
It is important to recognize, however, that there is no reverse procedure for establishing that a non-repeatable event has in fact occurred in the past, no matter how confident we are of the corresponding regularities. We have to look at the evidence available to us in the present and, for lack of a better word, guess. It just doesn't produce the same kind of confidence that the experimental procedure does because there's no good way to eliminate wrong interpretations. A proposition in physics suggests an experiment that might refute it. It faces, as Karl Popper would say, a severe test. A proposition in a historical science like evolutionary biology or geology faces the somewhat milder test of correlating the data. That is, it has to provide a satisfying explanation for the evidence, but since different people find different things satisfying, this isn’t quite so rigorous. The best we can do in this case is immerse ourselves in the appropriate body of evidence and evaluate it fairly (that is, without foregone conclusions), stay open to new approaches and cognizant of our own predispositions, and discuss our findings honestly. It remains the case, however, that we are dealing with interpretations.
Now, that doesn't mean all interpretations are equally valid. To return to Ken Ham, his interpretation is not a very good one because it doesn’t even pass the rather modest threshold outlined above. I don’t doubt his honesty, but he doesn’t seem to have a very good grasp on the evidence, and the view that the earth is about 6,000 years old simply makes nonsense out of the geological record, as well as radiometric dating methods on which our current estimation of the age of the earth rests. He’s clearly not evaluating the evidence without foregone conclusions, nor is he open to new approaches, since it is rather the point of his argument that he already knows that his particular reading of Genesis is the only right one. Thus on his approach, evidence that might disconfirm his theory is itself disconfirmed for that very reason. The conclusion is being used to evaluate the evidence, where the rational procedure would be to use the evidence to evaluate the conclusion. It’s as if our ballistics expert simply disregarded all the shell trajectories that didn’t correspond to his prior idea of what the underlying regularities were, or as if our fire investigator disregarded the evidence that a gas leak had caused the explosion because he already knew that it was the lab assistant’s fault. We might reasonably expect to derive a flawed theory from this flawed method, and indeed this has proven to be the case with Creationism. The problem is with the underlying disposition that it represents, or in other words with a refusal to take the evidence seriously.
Daniel Halverson is a graduate student studying the History of Science and Technology of nineteenth-century Germany. He is also a regular contributor to the PEL Facebook page.
Great post
Thanks
“It’s as if our ballistics expert simply disregarded all the shell trajectories that didn’t correspond to his prior idea of what the underlying regularities were…”
If you’re trying to posit a qualitative difference between two kinds of science, why did you use an example that explicitly refutes your point? Any physicist can deny that a regularity has been discovered using exactly this kind of maneuver.
“Evidence that disconfirms a theory” is different from evidence that “falsifies” a theory how, exactly?
Either you mean falsification in the strict logical sense, in which case no empirical theory is falsifiable, or you mean it in the loose sense, in which case the distinction you’re trying to draw evaporates.
Falsification is a special case of disconfirmation, one pertaining to failed predictions. Thus all falsification is disconfirmation, but not all disconfirmation is falsification. Lots of things can tend to disconfirm, i.e. undermine, a theory without involving predictions. The PEL podcast probably explains the specifics of Popper’s philosophy better than I can.
In addition to not explaining or giving examples of things that “disconfirm but don’t falsify” theories, you also forgot to explain whether you mean falsification in the strict logical sense (in which case, no empirical theory is falsifiable), or in the loose sense (in which case, both historical and nomological claims are equally falsifiable).
In either event, your distinction seems to be very much on the ropes.
please clarify: is the lab analogous to the universe? so we only have one lab or would need multiple universes to conduct the type of historical research you suggest on our universe?
I’m not sure I really understand the question. Can you elaborate a bit please?
I’m surprised you don’t mention the distinction between nomothetic and idiographic sciences, which seems to be what you’re talking about. (Or maybe you just didn’t want to clutter up the post with pretentious jargon.)
That’s it.
“Scientists point to Popper when asked how they do their business. I suspect that they endorse an eviscerated, but very sensible, version of Popper’s falsificationism. They think that Popper tells us that scientists test their theories against the world, and that scientists never invest their views with certainty. But Popper’s views are far more radical than that: Popper gives us no grounds for thinking that any scientific tests can ever have significance, because he ultimately denies any epistemic authority to scientific data. And he doesn’t merely say that scientists aren’t certain, he says they have no reason whatsoever to think their theories are close to the truth.”
Source: http://www.3ammagazine.com/3am/evolution-bioethics-and-human-nature/
this might be of interest:
https://podcasts.ox.ac.uk/series/physics-fine-tuning
I have a couple of remarks and questions here:
I was wondering what implications this might have for the kinds of extrapolations you find in cosmology. It seems that here we are also dealing with contingent, singular events (to some extent) which we are trying to give explanations for to the best of our abilities, using both our understanding of those regularities that we deem to be lawful, as well as the evidence available concerning the state of the universe and the objects that we find in it. Even though it is such a physics-heavy explanation, it seems that here, our only way for formulating any explanation involves our relying on an inference based on defeasible warrant (either we don’t have enough laws to rely on for our causal inferences, or we don’t have enough information to go on to make a reliable inference) and so someone like Ken Ham might just say that ‘well our physics cannot validate historical claims about the creation and development of the universe, so I’ll just rely on a particular text of revealed faith,’ or any other claim not currently supported by the consensus of astrophysicists/cosmologists. But I’m not sure any current astrophysicist/cosmologist considers what they are doing to be ‘historical science’ insofar as they are still relying on lawful explanations to generate their hypotheses.
This brings me to my next point. I’m not sure the example you used of the particular science lab burning down is appropriate to the context in question, since (as you indicated) the result could have been the result of human failing, but that this might not be ascertainable for certain. I’m not sure, but I think from a legal/forensic perspective, I think the going assumption is, that of course you can determine what happened, and that is why we have rigorous forensic investigation to ascertain what happened in a particular situation so as to: a) assign culpability to any person responsible for intentional (I’m not sure how natural science proves intentions in actions of human behaviour) or negligent conduct, and b) to ascertain what to do in order to prevent such an accident from repeating. Thus, on the one hand, once you get humans involved, you are going to be confronted with situation that just may be intractable from a natural scientific perspective, but nevertheless require answers for the sake of our practical interests. On the other hand, I think the explanation given for the singular event still has to fall within the parameters of what can be accepted as an explanation, i.e. we would not accept from a theoretical perspective that the lab blew up ‘for no reason,’ or ‘because God did it.’ It still seems that explanations have to fall within the pale of the explanatorily possible (or even probable). Thus, returning to Ken Ham, biology and geology are still sciences that rely on lawful regularities that they themselves discover, or are applied from related fields like biochemistry et al. Thus, there still seems to be parameters set for what can count as an objectively acceptable response, regardless of how high or low the threshold is for coming up with a theory that fits the data, since we are still dealing with what we assume to be lawful processes.
“I’m not sure how natural science proves intentions in actions of human behaviour…”
So, you literally have no opinion on why anyone other than yourself has ever done anything?
A guy says “I’m outta here,” twists a doorknob, pushes the door, and exits, and you are just 100% in the dark about whether his doorknob twisting was intended to open the door?
I did say later in the post that this aspect of human behavior is just intractable, i.e. there isn’t a physiological explanation available that would satisfy the question ‘why did he do it?’ When you’re trying to find out why the guy did what he did, it seems like the first thing people do is ask ‘why are you leaving?’ (unless of course it is clear from the context why the person is leaving). I don’t think people are going to observe the behaviour and go ‘let’s ask the neurobiologist about the state of his brain.’
There may be some explanations of this kind that would satisfy questions about human behaviour, but it is unclear to me whether this would be intentional behaviour, i.e. we could be satisfied with physiological explanations for someone who unsolicitedly blurts out “I’m outta here” and then does nothing to match his linguistic behaviour, we might think that the person is suffering from some condition where he just says things for no apparent reason.
By the way, this applies to self-scrutinising as well. Most of our conscious life may seem completely self-transparent to us, but when it comes to action, there is no way we can be sure that the motives we think we act on are the real motives. After all, we might be self-deceiving ourselves in order to justify or rationalise otherwise immoral behaviour. But here again, I don’t think that we can find the evidence of self-deception through rationalisation by observing certain neurons firing (at least not now, but my suspicion is that most of what we call intentional action is just in principle blocked from neurophysical explanation).
So of course I have opinions about people’s intentions, motives, and so on. I’m just not sure that these are opinions that involve knowledge of real regularities in the world that I use to generate an inference.
“I’m just not sure that these are opinions that involve knowledge of real regularities in the world that I use to generate an inference.”
I can’t speak to how things are done in your neck of the woods, but I invite you to visit the Stop sign at the end of my street some time.
As each motorist approaches the sign, we can place a friendly wager on whether my empirical models have given me any knowledge of “real regularities in the world” that I can use to generate an inference about their behavior, or whether your hypothesis that people behave randomly with respect to traffic signs is correct.
Unless you want to redefine a “real” explanation so that it only applies to ones couched in terms of the lowest level reducing base, in which case you’d have to defend why you’d want to speak in such an idiosyncratic way that practically none of what ordinary English speakers call explanations are “really” explanations.
The example of people stopping at stop signs has nothing to do with our biology. It’s a matter of convention. If traffic laws were changed today or tomorrow, such that everybody would not be required by law to stop, people might stop out of sheer force of habit, but I suspect over time people would not stop in front of them. Further, there is no guarantee that a driver will actually stop at a stop sign, just like there is no guarantee that they will stop at a red light (happened to a friend of mine by mistake one time while I was in the driver seat), or give right of way when the sign indicates (or when at a four-way intersection), or not park when the sign says don’t park (I’ve gotten traffic tickets before, and I bet lots of people have).
Giving a prediction based on real regularities occurring in nature is not going to give you any way of coherently explaining the behaviour of motorists on the road since traffic behaviour is inherently intelligent behaviour governed by social conventions. Maybe the Martian anthropologist might come up with some sort of inference based upon an assumed real regularity in nature, but I bet they will have to chuck them pretty quickly once they realise that we’re intelligent critters whose behaviour is governed by social convention more than it is by laws of nature. Thus, predicting that someone will observe traffic laws won’t be based on some sort of explanation of inherent features of traffic signs (I think the fact that they are signs should already tip one off to the fact that there is nothing inherent about the power that they command over our behaviour), nor will it be a combination of neurophysiology plus features of signs, nor (I hope) evolutionary arguments plus neurophysiology plus signs. To paraphrase McDowell/Wittgenstein, certain features of practices can only be explained from within the terms of those practices, thus already talking from within a ‘practical’ standpoint on what is going on there. If that allows me to avoid getting in traffic accidents, that still won’t guarantee my safety to the same degree that I can be sure that physical objects all act according to causal processes governed by e.g. gravity.
“The example of people stopping at stop signs has nothing to do with our biology.”
This reply would have some force if ‘regularity’ were a synonym for ‘biology’. Which it is not.
A regularity is just some pattern in observation. And there is a pattern in these observations, and this pattern is explainable by theories which quantify over intentions.
“It’s a matter of convention.”
This reply would have some force if ‘convention’ were an antonym of ‘regularity’, which it is not.
The antonym of ‘regularity’ is ‘irregularity’. I assure you, the traffic patterns on my street are highly non-irregular. Once again, I invite you to place a series of wagers on whether my empirical model of hominids who are averse to traffic tickets and high-speed collisions can perform better than chance in predicting hominid behavior in the presence of a highly visible Stop sign.
“If traffic laws were changed today or tomorrow, such that everybody would not be required by law to stop, people might stop out of sheer force of habit, but I suspect over time people would not stop in front of them.”
It’s almost as though one could use one’s experience with intentional beings to make an empirically testable model about how people would behave, and revise it in the face of evidence…
“Further, there is no guarantee that a driver will actually stop at a stop sign, just like there is no guarantee that they will stop at a red light (happened to a friend of mine by mistake one time while I was in the driver seat), or give right of way when the sign indicates (or when at a four-way intersection), or not park when the sign says don’t park (I’ve gotten traffic tickets before, and I bet lots of people have).”
This would be relevant if ‘knowledge of real regularities in the world that I use to generate an inference’ required exceptionless or infallible predictive power, which it does not. I think you have lots of knowledge about this sort of thing.
Personally, I would never get behind the wheel of a car if I thought other drivers’ behavior was literally random with respect to my past observations of it, and I haven’t really seen any disagreement on this.