Saving the symmetry principle V: symmetry without skepticism

To save the symmetry principle it is not enough to separate that principle from its false companions, as I have tried to do so far in this series. It is also necessary to show that adherents of the principle are likely to write better histories of science than those who flout it. In the previous post I defined the Symmetry Principle as the view that we should not reason from the truth or falsity of a belief to the goodness or badness of the believer's reasons for holding the belief. The best defense of this principle is simply to observe that sometimes past scientists have been right for the wrong reasons and wrong for the right reasons. But there's a problem with this defense: it seems to lead to radical skepticism about present-day science. In this post I want to show how we can accept the Symmetry Principle without abandoning present-day science or erecting artificial barriers between scientists and historians.


The fallacy is not always applicable

The Symmetry Principle states that it is a fallacy to go from truth-value to goodness-of-reasons. Before showing that this is indeed a fallacy, let me point out that it is not always a useful fallacy. To use the fallacy for a given belief, we would need to identify that belief as either true or false. The problem is that many past beliefs are neither strictly true nor strictly false, either because they are vague or because they are precise but only partly true. To make matters worse, some beliefs are still matters of mainstream debate.

Perhaps we could solve the problem of partially true beliefs by resolving them into truth and false components. Then we would infer that the true component was due to good reasons and the false component to bad reasons. This will not usually work, however. It is implausible to believe, for example, that Aristotle was guided by reason when he saw efficient causes in nature but driven by superstition or self-interest when he saw final causes. Surely those two ideas were too neatly joined in his mind to have such disparate origins.


Two unsound defenses of the Symmetry Principle

Nevertheless there are a fair number of historical disputes that have clear winners and losers. Kepler was right that the planets have elliptical orbits, or at least much more right than Galileo, who believed their orbits to be circular. The speed of light is finite, as Christiaan Huygens believed and as René Descartes denied. Heat is not a fluid, rock crystal is not made of frozen water, coral is not a mineral, and the moon is not translucent: most of us believe these claims even though each was hotly disputed at some point in the past.

Why should we apply the Symmetry Principle to these beliefs? A common answer is that they may turn out to be false. Maybe we will one day discover that the speed of light is infinite, and if that happens we would have to revise our history books to assign good reasons to Descartes and bad reasons to Huygens. But, so the argument goes, such post-hoc revisions would be absurd.

The problem with this argument is that it can be levelled against any procedure for generating beliefs about the past. Maybe we will one day discover that Descartes was the victim of a clever and mischievous type-setter who inserted his own ideas in key places in the philosopher's major works. Such a discovery would lead to a retrospective overhaul of Descartes scholarship. But the possibility of such revisions does not undermine our faith in textual analysis as a way of finding out about the past.

Another common answer is that it is simply not possible for the good reasons to fall on one side of a dispute and the bad reasons to fall on the other side. On this view, every party in every scientific debate is motivated by a roughly equal mixture of sound argument and corrupting self-interest. As per my last post in this series, I do not think this a good answer. All we can say with confidence is that there is a non-zero amount of both in the causal history of most beliefs. Deciding whether or not one kind of cause dominates in any given case is a matter for empirical investigation. (I suspect that the only reason people assert otherwise is that they conflate this assertion with the Symmetry Principle).


A better defense, and two diagnoses

So much for the wrong answers—what about the right ones? In my view the best answer to the symmetry sceptic is simply to list cases in which a famous past scientist held a true belief for a bad reason or a false belief for a good reason. As examples of the latter one need only think of Galileo, whose belief in the motion of the earth was partly based on an explanation of the tides that seems incoherent to us and that convinced very few people at the time. As examples of false beliefs backed by good reasons, one need only think of all errors that were not due to methodological sloppiness but to the unavoidable absence of key pieces of evidence. Ptolemy did not have the benefit of Galileo's telescopic observations when he built his world system; William Thomson had no knowledge of radioactive decay when he gave his first estimates of the age of the earth; etc. Many errors are due to bad luck, not bad method.

Given such examples, why would anyone want to deny the Symmetry Principle? And why do people sometimes violate the principle even though they should know better? I suspect that there are two factors at work. One is that some past beliefs agree so closely with present-day claims that the agreement cannot be due to coincidence. To continue with the speed of light example, the eighteenth-century British astronomer James Bradley (the subject of this recent blog post) gave a figure that was within 2% of the currently accepted value. Assuming that the current value is correct, it is absurd to think that Bradley made a lucky guess; he must had had good reasons for deciding on this value.

The problem is that many scientific theories, including some of the historically most interesting ones, are not of this kind. Often there are only a small number of theories to choose from, and in such cases there is plenty of room for lucky guesses. Way back in the fifth century BC, the Greek philosopher Empedocles maintained that the speed of light is finite. The fact that he was right about this does not tell us anything about the quality of his reasons for believing so, since even with the flimsiest reasons he would still have had a 50/50 chance of getting the right answer.

Overconfidence in the scientific method is the second factor that may lead to violations of the Symmetry Principle. Anyone who believes in a fail-safe method is bound to deny that false beliefs can be explained by that method. False beliefs must instead be explained by deviations from the true method, deviations brought about either by sheer carelessness or the action of self-interest, prejudice, religious convictions, etc.


A serious objection to the Symmetry Principle, and two bad replies

The argument from scientific method is one that historians of science are trained to dismiss out of hand. However there is no room for complacency here. There is a serious objection behind the appeal to method, an objection that we need to disarm if we want people to take the Symmetry Principle seriously. The objection goes like this:

Commonsense realism tells us that present-day scientists are a pretty good guide to the truth: if a large majority of the relevant experts say that a given theory is true, or that the theory is false, they are probably right. But the only way the experts can make these judgements is by examining the arguments for and against the theory. In other words, goodness-of-reason is a reliable guide to truth-value. It follows, as a matter of elementary logic, that the reverse is true, ie. truth-value is a reliable guide to goodness-of-reason. So far this argument applies only to present-day science. But there is nothing special about 2014, so it must hold for the past as well. Therefore historians are entitled to infer the goodness of a scientist’s reasons for a belief from the truth-value of that belief.

It would not be a good idea for historians to respond to this objection with a blanket denial of commonsense realism. Maybe commonsense realism is a misguided doctrine. But the fact is that the realism debate is still a live one among the relevant experts, namely philosophers of science, and it would not be wise for historians to ground their discipline on a form of skepticism that may be false and that many people reject. This would be an especially foolish move if historians intend to use their case studies to attack commonsense realism; to do so would be to assume what they are trying to prove.

Another false move is to say that commonsense realism is OK for scientists but not for historians of science (this move is sometimes called "compartmentalism" or "meta-relativism"). On this view, scientists are right to be realists and historians are right to reject realism. This will not do. If the claim is that scientific realism is true for scientists but false for historians, then the claim is guilty of an incoherent form of relativism. Perhaps the claim is instead that scientific realism is true tout court, but that it is methodologically suitable for historians to sideline this truth when they study past science. To say this is to restate the problem, not solve it. The challenge is precisely to reconcile realism with the methodological value of sidelining realism.


Some better replies to the serious objection

Here are some better replies to the objection that I raised in the previous section.

Firstly, the objection only applies to beliefs that enjoy a wide consensus among the relevant experts. If at time t there was no consensus about a given theory, then the objection does not apply to that theory at time t. The reason the objection does not apply to disputed past theories is that commonsense realism does not apply to disputed present theories (it makes little sense to be a realist about a given theory and its rival theories). Since the objection assumes commonsense realism, it has no purchase on theories that are under dispute.

This restriction is important because disputed theories are usually the ones that are of most interest to historians and sociologists of science. Consider again the question of whether the speed of light is finite or infinite. It would be no great loss to historians if they could only apply the Symmetry Principle to this question as it was answered prior to 1750, by which time most informed people were finitists about the speed of light.

The second reply is that empirical study is a better guide than philosophical inference when it comes to learning about a particular past event. In other words: however good the objection might be, it is no substitute for a careful study of the documents relating to the case that interests us, whether this is the disagreement between Huygens and Descartes over the speed of light, or nineteenth-century debates about natural selection, or whatever. Here's a World Cup analogy to illustrate the point: historians can ignore scientific realism when they study a particular case for the same reason that soccer fans can ignore the predictions of the pundits when they watch a particular match. It’s always worth checking what the result actually is, even if the predictions are right most of the time.

These seem to me to be the most straightforward replies. There are other replies that, though promising, are likely to be more controversial, either among philosophers or historians or both. One is to accept that the objection holds for recent science but deny that it holds for earlier periods, on the grounds that evidential standards were lower in the past than they are now. In the early modern period, even the best reasons were not that good, and as a result they did not track the truth as reliably as today’s precision instruments and randomised controlled trials.

Another promising reply is to accept commonsense realism about today’s empirical laws—such as the rules of geometric optics—but reserve judgement about today’s high-level theories—such as string theory. This is a perfectly respectable move within the philosophy of science, and it would restrict the scope of the objection in question so that it only applied to past empirical laws and not to high-level past theories. That way we would be free to apply the Symmetry Principle to the eighteenth-century debate over the nature of vis viva, the nineteenth century debate over the existence of the ether, and so on.

If you can think of other replies, controversial or otherwise, please feel free to post them in the comments below. For the moment, I hope to have shown that the objection is strong enough to take seriously but not strong enough to scupper the Symmetry Principle. That principle is compatible with confidence in present-day science. There remains the question of whether anti-realism is worth retaining as a heuristic device when writing about past science. In my next post I will argue that it is not worth retaining. In fact, if you need this device then you have not understood the Symmetry Principle. Expand post.

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Critical thoughts on Howard Hotson's Scientiae keynote

What is intellectual history and how can we justify this sub-field to our peers and pay-masters? Those were the questions that Howard Hoston tackled in a rousing keynote address at the Scientiae conference held at the University of Vienna in the last week of April. Hotson's questions were bracing because the Scientiae conferences--this year's event was the third in an ongoing series--are founded on the idea that intellectual history is a coherent and important field of study. Hotson's answers included a provocative argument against managerial meddling in the humanities, namely that past actors (and especially early moderns) achieved great things in the absence of such meddling. I'll summarise Hoston's talk before explaining why I think this argument fails.

Hotson began by observing that intellectual history is marginal to the discipline of history. His point was not that practitioners of intellectual history are marginal--after all, Hotson himself is a distinguished professor at a respected university. His point was instead that practitioners of intellectual history find it hard to ply their trade under that banner. Instead they attach themselves to various sub-fields--such as art history or Church history or Renaissance history--depending on the topics they happen to be researching at any given moment. Over the course of a career, an intellectual historian may join many different scholarly communities, and make a solid contribution to them all, without ever feeling truly at home in any of them.

Why is this so? Why are intellectual historians "stateless citizens in the Republic of Letters"? Hotson's answer was simple. Almost by definition, intellectual historians are those who trace the histories of the disciplines that make up the present-day university. As a result, any given practitioner of intellectual history is drawn towards the present-day discipline whose past she investigates. Historians of philosophy are tugged in the direction of philosophy; historians of physics have one foot in physics departments; art historians have umbilical ties to artists; and so on.

These disciplinary ties have two consequences, according to Hotson (and here I simplify his argument to the point of distortion). Firstly, they tend to lessen intellectual history in the eyes of other historians, who are suspicious of scholars who consort with the present while claiming to study the past. The other effect of disciplinary ties is that they weaken the inter-disciplinary ties that would otherwise bring together different bands of intellectual historians into a single, stable tribe. Historians of physics (for example) will not merge with historians of theology until the former have diverged from physicists and the latter from theologians.

Given this diagnosis, one might think that the best remedy for the rootlessness of intellectual historians is for all of them to move into history departments. I think it is fair to say that Hotson equivocated on this point. At one point in his talk he clearly stated that intellectual historians are better off in history departments than they are in the departments of the disciplines they study. Later in the talk he appeared to reconsider this judgement in light of the great diversity of institutional arrangements that one finds across Europe and North America. In the UK, where many philosophers are stridently a-historical, a historian of philosophy is indeed better off in a history department. But the same may not be hold in France or Italy, where philosophy is already a quasi-historical discipline. So intellectual historians may not need to move out of their home departments in order to collaborate with each-other. The important point--here Hotson was unequivocal--is that such collaboration is necessary if we want to unify the field of intellectual history and thereby bring it in from the academic cold.

So far Hotson had been learned and insightful but not provocative. He ended his talk with what he candidly called a "polemical twist." Why should intellectual historians collaborate with eachother, and more generally why should they be free to choose who they collaborate with? The answer that Hotson offered is that open collaboration of this kind was responsible for some of the most important breakthroughs in the history of thought, and in particular for the bursts of human creativity that are sometimes called the Renaissance and Scientific Revolution. If it worked in the past, it will work again. If we want to emulate Leonardi da Vinci or René Descartes (and who doesn't?) we should start by adopting their interdisciplinary approach. I'll call this argument the optimistic induction (not to be confused with its pessimistic cousin).

At this point it is worth noting that Hotson has been a vocal critic of UK higher education policy, speaking out against the government's plans to run universities along free-market lines. He is especially critical of schemes that reward academics for doing research that "meet[s] the demands of industry" or that is "tied to party-political slogans." These schemes "impoverish teaching, undermine creativity, trivialise research, and alienate teachers." Hotson intended his optimistic induction as an argument against these external influences on research agendas. He also intended it as an argument for interdisciplinary intellectual history. In my view the argument misses both of these targets.

The problem with the second target is that the argument works at least as well for disciplinary collaboration as it does for interdisciplinary collaboration. Why? Because the creativity of the early moderns drew on both kinds of collaboration. It is true that early modern historians wrote books that covered (what we would call) the histories of art, politics, and science. But it is also true, for example, that advances in astronomy were due partly to re-interpretations of the history of astronomy (here I am thinking of Johannes Kepler's Defense of Tycho Against Ursus, written in 1600). Indeed, before about 1760 the history of science barely existed as an area of study independent of the sciences whose past it described.

There are also two other problems with the optimistic induction. The first is simply that the present is not always like the past. The fact that open collaboration worked for Da Vinci and Descartes does not mean that it will work in the 21st century. This is a problem for any induction, of course. But it is especially sharp in this case because intellectual historians make much of the fact that the early modern disciplines were completely different from the disciplines of today's universities. Indeed, this is a common argument in favour of collaboration between historians of different disciplines, an argument that Hotson used himself in his keynote. We are asked to believe that the fruitfulness of interdisciplinary collaboration is a historical constant even though the structure of the disciplines is not. More is needed to defend this paradoxical premise.

The other, related problem is that intellectual creativity did not end when the modern-day disciplines began. Indeed, historians of science can cite at least one example of intellectual ferment that was accompanied by decisive steps towards the modern disciplines. This is the episode known as the second scientific revolution, a period around 1800 which saw the creation of new disciplines such as geology and biology and the reconstitution of old ones like physics and physiology. Many leading scientists in this period worked across these new disciplines, but on the whole they were more specialised than the likes of Descartes or Boyle or Newton.

The optimistic induction is even less apt for Hotson's other target, namely political and economic interference in research agendas. The optimistic induction may not support present-day interdisciplinary research, but at least there is a consensus that early modern intellectuals were an interdisciplinary bunch and that their boundary-crossing was one source of their creativity. There is no such consensus when it comes to the scale or fruitfulness of political and economic pressures in early modern intellectual life. If anything, recent research shows that these pressures were greater in the early modern period than we previously thought, and that they nourished intellectual life rather than starving it.

This is surely true for historians of science, who for several decades have been arguing that the intellectual achievements of the scientific revolution were linked in one way or another to political or economic or military agendas. Galileo's discovery of the moons of jupiter was a move in a patronage game; the motion of cannonballs inspired the mechanical philosophy; Lavoisier the chemist used the same accounting methods as Lavoisier the tax farmer; and so on. If there is a lesson in these examples it is not that the humanities should resist the advances of politicians and economists and entrepreneurs but that resistance is neither possible nor desirable. Doesn't history teach us that intellectual life is always political? Don't we know that the military and the market-place are cultural resources that the greatest thinkers have used to their advantage?

These questions are awkward not just for Hotson but for any historian who places past thinkers in context while trying to free herself from her own context. There are various ways around this dilemma, and probably Hotson is aware of both the dilemma and the solutions. However his optimistic induction ignores the dilemma rather than solving it. There are good arguments against current UK higher education policy, and Hotson has articulated these arguments in compelling ways in his public appearances. He is also right to urge academics to use their intellectual resources--such as their knowledge of history--to defend those resources against creeping corporatism in universities. However the optimistic induction is not the best way to do this. Expand post.

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