Auxiliary Hypotheses

How Philosophy of Science Relates to Scientific Practices | Angela Potochnik

It’s widely appreciated that contemporary philosophy of science, when done well, engages with actual scientific practices. Philosophers should not sit back (in armchairs, of course), consider what we think good science would look like, then inform scientists of our findings. Rather, current thinking goes, we should take seriously what scientists actually do, using these practices as the starting points for our philosophical accounts of the aims, processes, and products of science.

The Metaphysical Status of Quantities | J. E. Wolff

 

Paradigmatic physical attributes, like energy, mass, length, charge, or temperature are quantities. That these attributes are quantitative is important for experiments (they can be measured), as well as theories (we can formulate quantitative laws that hold between them). Quantities are arguably central to science, and especially to the physical sciences.

Compatibilism about Chance and Determinism | Nina Emery

Suppose that it is already determined that the coin I just flipped will land heads. Can it also be the case that that very coin, on that very flip, has some chance of landing tails? Intuitively, the answer is no. But according to an increasing number of contemporary philosophers, especially philosophers of physics, the answer is yes.^[1]

 

According to these philosophers there are non-trivial chances (chances between zero and one) in worlds where the fundamental dynamical laws are deterministic. In such worlds, at any time t, for any event e, it is already (at t) determined that e will happen or that e will not happen. Nonetheless, these philosophers say, in at least some such worlds and for at least some events, the chance of those events happening is between zero and one. Call the chances that are supposed to exist in such world ‘deterministic chances’, and the view that there are such chances ‘compatibilism about chance and determinism’, or for brevity just ‘compatibilism’.

 

Should we endorse compatibilism? You might think that before we can answer this question we first need to answer the question of what sorts of things chances are in general. (Is the chance of some event happening just the relative frequency with which that type of event happens? Or is it something more metaphysically robust, like the propensity of certain set-ups to produce that type of event? And if the latter, what on earth is a propensity?) But there’s good reason to think that we might be able to make significant progress on the question of whether to be compatibilists even if we aren’t yet willing to take a stance on the metaphysics of chance more generally. To see why, it’s helpful to keep in mind the following two distinctions.

 

First, it is helpful to distinguish between arguments that merely establish what I will call ‘weak compatibilism’, on the one hand, and arguments for ‘robust compatibilism’, on the other. Weak compatibilism about chance and determinism is the view that deterministic chances are merely metaphysically possible. Robust compatibilism is the view that deterministic chances are more than merely metaphysically possible—they exist either in the actual world or in some relatively nearby worlds. Versions of robust compatibilism can be differentiated depending on which sorts of nearby worlds they target, but of particular interest are those worlds in which our best deterministic scientific theories—like Bohmian mechanics, a deterministic interpretation of quantum theory—are true.

 

Arguments for weak compatibilism take the form of arguments against supposed platitudes about the nature of chance that seem to rule out any possibility of deterministic chance. Take, for instance, the highly intuitive thought that if there is a non-trivial chance of something happening, then it must be possible for that thing to happen and possible for it not to happen. Some philosophers (for example, Schaffer [2007]) endorse something like the following principle as a way of capturing this thought:

The Chance–Possibility Platitude (Incompatibilist Version): If the chance, at world w, at time t, of event e is greater than zero, then there exists a world, w', such that (i) w' matches w in laws, (ii) w' and w have the same micro-physical history up until time t, and (iii) e happens at w'.

According to the incompatibilist’s version of the chance–possibility platitude, if there is a non-trivial chance of something happening at some time, then it must be possible for that thing to happen and possible for it not to happen, while holding fixed both the history of the world up until that time and the laws of nature. It follows that in a deterministic world (where at any time, for any event e, it is already (at t) determined that e will happen or that e will not happen), the chance of some event happening is always either one or zero.

 

In (Emery [2015a]), I argued against the incompatibilist’s version of the chance–possibility platitude on the grounds that either it was based a highly contentious and unpopular view about the nature of time, or it was based on considerations that supported eliminating chance—deterministic or not—from our theories altogether. Given the important work that chances do for us in science, in philosophy, and in everyday reasoning, I take eliminativism about chance to be a non-starter.

 

This sort of argument is an argument for weak compatibilism. It removes a reason for thinking that the nature of chance itself makes deterministic chance impossible. If it succeeds, it gets us at least one step closer to thinking that deterministic chances are metaphysically possible. (How close precisely depends on what other supposed platitudes regarding the nature of chance are waiting in the wings.) But it doesn’t do anything to establish that deterministic chances exist in the actual world, or in any relatively nearby worlds.

 

What sort of arguments are there for robust compatibilism? Here is where the second distinction becomes helpful. On the one hand, there are metaphysics-based arguments for robust compatibilism; on the other, there are role-based arguments. Metaphysics-based arguments start from some particular metaphysical analysis of chance—various forms of frequentism, versions of the so-called best systems analysis, propensity theories, or what have you—and then argue that given this analysis, there are chances in relatively nearby worlds where the fundamental laws are deterministic. Perhaps most obviously, this sort of argument is readily available to those who endorse straightforward versions of frequentism. (Of course, there are non-trivial relative frequencies in relatively nearby worlds where the fundamental laws are deterministic, the argument would go; so, there are non-trivial chances in such worlds.) But following Albert ([2000]) and Loewer ([2004]), many advocates of the best systems analysis (according to which chances are those probability functions that appear in the simplest, most predictively powerful summary of the actual patterns of events) have also given metaphysics-based arguments for robust compatibilism.

 

Role-based arguments, by contrast, start from some particular role that probabilities are supposed to play—in our best scientific theories, in our philosophical theorizing, in our everyday reasoning, or what have you—in relatively nearby deterministic worlds, and then argue that in order to play that role, the probabilities in question must be objective—they must be genuine chances.

 

For my own part, I am more interested in role-based arguments for robust compatibilism than I am in metaphysics-based arguments. For one thing, metaphysics-based arguments are inevitably as contentious as the metaphysical analyses that they are based on. They tend to do little to change the minds of those who are initially sceptical of compatibilism. But also, as I argue in (Emery [2017]), role-based arguments are some of the strongest arguments we have in metaphysics. After all, such arguments are often used to license the introduction of weird or novel entities in science. And while metaphysicians are hardly limited to the methodology of science, insofar as they make use of that methodology, their arguments are all the more convincing.

 

If you attend to our best deterministic scientific theories, it might seem at first that a role-based argument for deterministic chance is straightforward. Start from the fact that some of our best deterministic scientific theories involve probabilistic predictive rules. (Think, for instance, of Born’s rule, as it plays a role in interpretations of quantum phenomena, including Bohmian mechanics. Born’s rule says that the probability that a system with wave function  at t will be found in configuration c if we perform a measurement on it at t is given by.) This is the first premise of the argument. The second premise is that any probabilities that play a role in the predictive rules of our best scientific theories are objective probabilities.

 

On the face it, this may look like a decent argument for robust compatibilism, but after more careful examination, I find myself unconvinced. In particular, I think that whether we should endorse the second premise depends on what we mean by ‘objective’. If we mean something like ‘wholly independent of the beliefs we have, the evidence available to us, and the ways in which creatures like us reason’, then it seems as though probabilities could play a role in the predictive rules of our best scientific theories without being objective. Maybe the predictive rules of our best scientific theories depend in part on the ways in which creatures like us reason or the sorts of evidence that are available to us.

 

In (Emery [2015b]), I described a different role-based argument for robust compatibilism, which I think is more promising, though also much more complicated. This argument starts with the role that probabilities play in determining the truth conditions of counterfactuals (Lewis [2016]). For example, one natural account of those truth conditions is that the counterfactual ‘if I had dropped this glass just now, coffee would have spilled all over the floor’ is true if and only if in the nearest world where I dropped the glass just now, coffee was very likely to spill all over the floor. (Or if, like Hajek ([unpublished]), you think that most counterfactuals are not true, it starts with the role that probabilities play in determining the assertibility conditions of counterfactuals. ‘If I had dropped this glass just now, coffee would have spilled all over the floor’ is not true, but it is assertible if and only if in the nearest world where I dropped the glass just now, coffee was very likely to spill all over the floor.) Given the important role that counterfactuals play in scientific theorizing (for example, in theorizing about which universal generalizations are laws, or in theorizing about which properties of a system depend on others and which do not), if probabilities play a role in determining the truth (or assertibility) conditions of counterfactuals, then those probabilities must be objective. Or so I argued.

 

Lately I’ve been thinking more about a different, and to my mind even more promising, role-based argument for robust compatibilism. This argument starts from the explanatory role that probabilities play in our best deterministic scientific theories and argues that in order to play that role, such probabilities must be genuine chances. This argument is often suggested in the literature, but has rarely been developed in detail.^[2]

 

One reason to be especially interested in this sort of explanatory role argument is that if it works, it has the potential to suggest a novel metaphysics for deterministic chance. Thus far, most proponents of deterministic chance in the literature tend to be Humeans, in the sense that they think that the laws and chances in each world are determined (in some important sense) by the patterns of events that actually occur in those worlds. But it is well known that Humean analyses of laws have trouble justifying the explanatory power of laws (Armstrong [1985]; Maudlin [2007]). After all, if the laws are determined by the patterns of actually occurring events, how can they also explain those patterns of events? And it is plausible to think that similar worries will trouble Humean analyses of chance (Emery [2017]). So insofar as it is the explanatory role that deterministic chances play that motivate us to be compatibilists, we may end up adopting a more metaphysically robust, non-Humean account of such chances. Allowing such chances into their ontology will violate the scruples of many a Humean metaphysician and philosopher of physics. But recall what I mentioned earlier about role-based arguments: such arguments are often used in science to introduce weird or novel entities. Indeed, there’s a natural reading on which the introduction of all sorts of strange or sui generis scientific entities—from the electromagnetic field, to the wave function, to the neutrino, to dark energy—was originally, or still is, justified by the explanatory role that those entities play. So insofar as a plausible explanatory role argument forces us to posit deterministic chances—and non-Humean deterministic chances at that—even the Humeans among us may be forced to set their scruples aside.

 

Mount Holyoke College

 

References

Albert, D. Z. [2000]: Time and Chance, Cambridge, MA: Harvard University Press.

Armstrong, D. M. [1985]: What Is a Law of Nature? Cambridge: Cambridge University Press.

Emery, N. [2015a]: ‘Chance, Possibility, and Explanation’, British Journal for the Philosophy of Science, 66, pp. 95–120. 

Emery, N. [2015b]: ‘The Metaphysical Consequences of Counterfactual Skepticism’, Philosophy and Phenomenological Research, 94, pp. 399–432. 

Emery, N. [2017]: ‘A Naturalist’s Guide to Objective Chance’, Philosophy of Science, 84, pp. 480–99. 

Glynn, L. [2010]: ‘Deterministic Chance’, British Journal for the Philosophy of Science, 61, pp. 51–80.

Hájek, A. [unpublished]: ‘Most Counterfactuals Are False’.

Handfield, T. and Wilson, A. [2014]: ‘Chance and Context’, in A. Wilson (ed.), Chance and Temporal Asymmetry, Oxford: Oxford University Press, pp. 19–44.

Hoefer. C. [2007]: ‘The Third Way on Objective Probability: A Sceptic’s Guide to Objective Chance’, Mind, 116, pp. 549–96. 

Ismael, J. T. [2009]: ‘Probability in Deterministic Physics’, The Journal of Philosophy, 106, pp. 89–108. 

Lewis, K. S. [2016]: ‘Elusive Counterfactuals’, Noûs, 50, pp. 286–313. 

Loewer, B. [2001]: ‘Determinism and Chance’, Studies in History and Philosophy of Modern Physics, 32, 609–20. 

Loewer, B. [2004]: ‘David Lewis’s Humean Theory of Objective Chance’, Philosophy of Science, 71, pp. 1115–25.

Maudlin, T. [2007]: The Metaphysics within Physics, Oxford: Oxford University Press.

Meacham, C. J. G. [2005]: ‘Three Proposals Regarding a Theory of Chance’, Philosophical Perspectives, 19, pp. 281–307. 

Schaffer, J. [2007]: ‘Deterministic Chance?’, British Journal for the Philosophy of Science, 58, pp. 113–40.

 

Notes

^[1] See, for example, (Loewer [2001]; Ismael [2009]; Hoefer [2007]; Glynn [2010]; Handfield and Wilson [2011]; Emery [2015a], [2015b]).

^[2] See (Albert [2000]; Loewer [2001]; Meacham [2005]; Emery [2015a]).

 

Image credit: Georges de la Tour, 'The Dice Players'

A Hot Mess: Inflation and Fine-Tuning | Casey McCoy

 

On the first page of his preface to the English edition of The Logic of Scientific Discovery, Popper writes:

I, however, believe that there is at least one philosophical problem in which all thinking men are interested. It is the problem of cosmology: the problem of understanding the world—including ourselves, and our knowledge, as part of the world. All science is cosmology, I believe, and for me the interest of philosophy, no less than of science, lies solely in the contributions which it has made to it. For me, at any rate, both philosophy and science would lose all attraction if they were to give up that pursuit. (p. 15)

Popper states here the classic, inclusive view of cosmology as the study of the all-inclusive, big ‘U’ Universe. Given the suggested philosophical nature of cosmology, it may seem somewhat surprising that philosophers have paid relatively little attention to the physical study of cosmology, namely, what one might call the science of little ‘u’ physical universes. (For the difference between Universe and universe, have a look at Edward Harrison’s classic textbook on cosmology, Cosmology: The Science of the Universe; it’s the book that first got me interested in the subject.) If philosophy aims at understanding the Universe, then surely an important piece of the complete story is to be found in its physics.

Sommerfeld’s Miracle: The Ultimate Challenge to Scientific Realism | Peter Vickers

  Arnold Sommerfeld (left) and Paul Dirac (right)

A ‘no miracles’ argument is still prevalent in the scientific realism debate, even if a lot has changed since Hilary Putnam’s formulation of it, and even if the word ‘miracle’ is generally avoided. For example, realists think that if the most central ‘working’ parts of a scientific theory were not even approximately true (for any serious theory of ‘approximate truth’), then it would be incredibly unlikely (‘miraculous’) for that theory to deliver successful novel predictions with ‘perfect’ quantitative accuracy (e.g. to several significant figures). It would be like perfectly predicting the time and position of the next solar eclipse based on a completely false (not even approximately true) model of how the sun, moon, and earth interact. Here it is appropriate to talk in terms of ‘counterexamples’ to scientific realism: any historical case where a scientific theory delivered ‘perfect’ predictions but where the central working parts of the theory are now thought to be radically false would be a very serious thorn in the side of nearly every contemporary scientific realist position.

 

How many such ‘counterexamples’ are there in the history of science? Are there any at all? For more than twenty years, the main historical challenges to scientific realism were those on Larry Laudan’s famous ‘list’. Nearly all of these examples are now quite widely considered (by realists at least!) to be somewhat less dramatic for realism then they perhaps initially appeared: either the success achieved by the false theory is only quite impressive, or else the confirmation resulting from that success can reasonably be seen to extend to only certain ‘working’ parts of the theory, which are indeed approximately true. So why weren’t there tougher historical challenges on Laudan’s list, cases where the success was hugely impressive and where the most central parts of the theory were not even approximately true? Is it because such cases don’t exist, because the scientific realist is basically right in her conviction that there are no ‘miracles’ in science?

 

I know of one such ‘miracle’. Even physicists, with no knowledge of the scientific realism debate (including Heisenberg) have been inclined to call it a ‘miracle’. It is widely referred to in the physics literature as a remarkable coincidence (‘perhaps the most remarkable numerical coincidence in the history of physics’, according to Ralph Kronig writing in 1960) and one physicist has even called it a ‘cosmic joke’. Without any intention, these remarks directly challenge the central ‘no miracles’ or ‘no cosmic coincidences’ argument for scientific realism.

 

Figure 1. Part of the hydrogen emission spectrum: only light of very specific frequencies is emitted from hydrogen. The fine structure is not visible here.

 

The case concerns Arnold Sommerfeld’s 1916 derivation of the ‘fine structure formula’, which predicts the frequencies of the spectral lines of hydrogen. The theory leading to the formula built on Bohr’s much simpler model of the hydrogen atom, which had been able to account for the ‘gross’ structure of the hydrogen emission spectrum (specific frequencies of light that are emitted from hydrogen; see Figure 1). But it turns out that when one looks at this gross structure through a high resolution spectroscope, each line is actually not a single line, but two or more lines grouped very closely together. This is the ‘fine structure’, a phenomenon Bohr’s model was incapable of explaining.

 

Between 1913–16, Sommerfeld developed Bohr’s model, introducing elliptical orbits, a second quantum number, and relativistic corrections. These were all well-motivated de-idealizations, and indeed Bohr himself had attempted (without success) to de-idealize in this way. The de-idealizations led to the fine structure formula, which, it turns out, perfectly predicts the fine structure of the hydrogen spectral lines. That is, it gives exactly the same formula as the fully relativistic Dirac quantum mechanics of 1928, and it gives better predictions for this phenomenon than basic (1925) Schrödinger–Heisenberg quantum mechanics. Since the success is so dramatic, the realist would dearly like to explain the success in terms of the (approximate) truth of the central working parts of Sommerfeld’s theory (dismissing the radically false parts of the Sommerfeld theory as ‘idle wheels’). However, Sommerfeld reached his formula by considering the velocity variations for an electron in an elliptical orbit, and the variation of electron mass with velocity as dictated by special relativity. There seems to be a clear dependence relation here between the final formula and (what are now taken to be) radically false assumptions. As Griffiths notes in his popular textbook Introduction to Quantum Mechanics: ‘It’s not even clear what velocity means in QM’.

 

Despite this drama, the realist is not without options. First, consider the suggestion that a realist commitment to Sommerfeld’s theory was in fact not warranted, for two separate reasons: (i) although Sommerfeld’s success vis-à-vis the fine structure formula was astonishing, the theory also had some significant failures (e.g. spectral line intensities), and a realist inclined towards Bayesian updating might insist that after iterating one’s degree of belief in the theory given all available evidence, one’s final degree of belief might not be very high; (ii) the scientific landscape was changing rapidly at that time (1916–25), and perhaps a cautious realist should not make a realist commitment to any theory, however successful, until a few years have passed and the dust has settled.

 

However, concerning (i), usually a doxastic commitment is thought to be warranted in the face of (‘normal’) anomalies so long as the successes are good enough. And on (ii), Sommerfeld’s success came in 1916, and the theory vis-à-vis the hydrogen atom still looked like the ‘complete truth’ to mainstream physicists nine years later in 1925 (as detailed by Helge Kragh in his excellent paper, ‘The fine structure of hydrogen and the gross structure of the physics community, 1916-26’). They certainly thought they had been cautious enough, and the realist might be wary of insisting that scientists made a big mistake in their epistemic judgements.

 

What if the realist accepts that a realist commitment is necessary? Can she hold out hope that a certain sort of doxastic commitment, to certain features of Sommerfeld’s theory, can in fact be sustained? It is hard to see how a standard selective realist move could work, given the radical discontinuities between the two theories. Lawrence Biedenharn’s paper, ‘The “Sommerfeld Puzzle” Revisited and Resolved’, sounds very promising for the realist(!), but it is far from clear that the ‘resolution’ in this paper is what the realist is after. For example, Biedenharn certainly does not demonstrate that Sommerfeld’s derivation can succeed without reference to continuous worldline orbital trajectories (something totally absent from Dirac’s theory), nor does he demonstrate how Dirac’s derivation can succeed without reference to electron spin (something totally absent from Sommerfeld’s theory). And these are perhaps the two most important things on the realist’s to-do list here.

 

Apart from Biedenharn, there is one other prominent attempt in the physics literature to resolve the puzzle. Stefan Keppeler (‘Die “alte” Quantentheorie, Spin präzession und geometrische Phasen’) makes use of a semi-classical approach to Dirac quantum mechanics, and uses this to derive the fine structure formula. He then makes a comparison with Sommerfeld’s derivation, and concludes that Sommerfeld succeeded because two missing terms happen to cancel each other out. Thus Keppeler favourably quotes Yourgrau and Mandelstam, who in 1951 had already written, ‘Sommerfeld's explanation was successful because the neglect of wave mechanics and the neglect of spin by chance cancel each other in the case of the hydrogen atom’. If this is right, it wouldn’t be very satisfying for the realist: on Keppeler’s explanation, the success remains ‘miraculous’, since it is miraculous that the two errors exactly cancel each other. Even the most conscientious selective realist certainly would go wrong in her doxastic commitments, since Sommerfeld’s classical approach is definitely not ‘idle’ for Keppeler. It’s just somehow ‘pure luck’ that Sommerfeld’s approach gives the right results given that his mechanics is wrong and that he neglects the effect of electron spin.

 

That isn’t the end of the story, however, since Biedenharn’s analysis indicates a possible mistake in Keppeler’s reasoning. He insists that ‘Sommerfeld's success is not at all a matter of blind luck’ and writes: ‘It is now clear that the argument of Mandelstam and Yourgrau (that Sommerfeld succeeded "because the neglect of wave mechanics and the neglect of spin effects by chance cancel each other") cannot be correct’. The reason is that Biedenharn takes his analysis to have shown that ‘wave mechanics per se makes no change in the answer’, in which case this can’t be one of the two errors that cancel each other out.

Thus a hope remains for the realist that the right application of selective realism might yet explain the puzzle in realist terms. Biedenharn’s claim that there is ‘the closest possible correspondence between the two (suitably formulated) calculations’ and a ‘most remarkable and detailed correspondence between the Sommerfeld procedure and the quantal solution’ suggests, perhaps, that some sort of structural realism might fit this case rather well. That is, if the realist restricts her doxastic commitment in this case to ‘high level structure’, it might be possible to be a realist here without committing to ‘radically false’ claims about the underlying nature of hydrogen. Of course, the standard (causal) explanation of the fine structure within modern quantum mechanics makes essential use of electron spin, but this doesn’t rule out an alternative, non-causal (structural) explanation of the fine structure where spin plays no role.

 

Whatever the case, it is hard to get away from the idea that there is something miraculous about Sommerfeld’s success. For example, supposing the basic structure of Sommerfeld’s theory (or at least the working part of Sommerfeld’s theory) is indeed identical to some underlying structural features of Dirac quantum mechanics, it would still be a miracle that Sommerfeld managed to hit upon that structure, given the purely classical, concrete physical ideas that dictated the content of his theory. But in fact this isn’t a problem for the scientific realist; it just goes to show that the ‘no miracles argument’ is a misnomer, since miracles of a kind are perfectly compatible with realism. What the realist needs is a principled, non-ad-hoc restriction on the scope of confirmation of a theory achieving significant predictive success. So long as the realist does not end up doxastically committing to something that is radically false, she is in the clear. And, notwithstanding appearances to the contrary, that does remain possible vis-à-vis the Sommerfeld miracle. The realist is surely bruised, but not beaten. And if the realist can indeed turn this case around, that would be quite something.

Durham University

Making Sense of Scents: The Science of Smell | Ann-Sophie Barwich

 

 

In 1914, Alexander Graham Bell proposed a challenge:

Did you ever try to measure smell? Can you tell whether one smell is just twice as strong as another? Can you measure the difference between one kind of smell and another? It is very obvious that we have very many different kinds of smell, all the way from the odour of violets and roses up to asafoetida. But until you can measure their likeness and differences you can have no science of odour.

This challenge remains unanswered today. However, it has been taken up.

Olfaction is a fairly young model system in sensory neuroscience. Before the discovery of the mammalian olfactory receptor genes by Linda Buck and Richard Axel in 1991, only a few dedicated scholars were trying to make sense of scents. For centuries, smell did not attract much attention from scholars in the sciences nor the humanities. One major reason for this neglect is suggested in in the opening quote by Bell. The sense of smell is incredibly hard to study in a controlled setting. For most of the history of science, olfaction has thus been set aside for its apparent lack of testability. While we have a better understanding of the olfactory pathway today, many of the central questions remain unresolved. How do you classify smells and how do you make their perception comparable? (And how do you control the volatile stimulus, its concentration, and its administration in psychophysical studies?) What are the perceptual dimensions of smell? Are there such things as primary odours? How does the brain represent smells? From this perspective, the discovery of how the sense of smell works presents us with an intriguing, yet untold, history of creativity in scientific reasoning. What is more, the crucial part of this history is contemporary!

My research is a current and cross-disciplinary analysis of olfaction as a new model system for the senses and in neuroscience. My focus is on scientific decision-making in laboratory practice. What kinds of epistemic and pragmatic factors influence the choice of concepts, the design of experimental strategies, and the interpretation of data in scientific practice? Must we consider different philosophical arguments about the advancement of science when we deal with ongoing research instead of historical case studies? Large parts of the philosophy of science have dealt with past science. Almost all central ideas in debates on such topics as model-choice, scientific progress, or the problem of underdetermination of theories by evidence have been developed and tested against historical case studies. Furthermore, support for our philosophical theories rests primarily on selected resources from the literature. The question that arises is how different our central concepts (such as empirical success) would be if we were to look at ongoing and present practice. What empirical, epistemic, and social factors did we miss that analysis of current practices can reveal, and that might shed further light on our studies?

I am interested in the conceptual foundations of (neuro)science, and I analyse the uncertainties and ‘missing knowledge’ that drive contemporary research. In the tradition of HPS, I also recover the hidden record of olfactory experiments in past science (from 1600 onwards) to analyse the creative strategies that a few dedicated scholars have used to make the sense of smell scientifically accessible. My approach towards integrating these historical ideas into current practice involves identifying older studies that are relevant to similar experimental set-ups today. One such example concerns the parallels I have found between the study of airflow patterns in the nasal cavity in nineteenth-century physiology and the modern recreation of these airflow patterns through 3D printing.

The study of smell provides an important opportunity to make philosophical and historical ideas central to experimental practice because almost all key players in the scientific development of the study of smell are actively conducting research. And this is where philosophical analysis meets science in a complementary fashion; the perceptual dimensions of smell are an open issue in both philosophy and science. For this reason, I work in close collaboration with the lab of Stuart Firestein at Columbia, and I am in contact with additional neuroscience and food-science laboratories at other US universities, in order to address three questions: How should we model the perceptual structure and the hedonic (affective) or aesthetic experience of smell? Is olfaction different to other sensory systems such as vision? And how are smells represented in the brain?

You may ask what characterizes smell as a model system for research on the senses. Recent studies in olfaction promise new insights into molecular biology and neuroscience. And these insights present a good incentive to rethink our traditionally visuo-centric approaches to perceptual analysis. Indeed, the difficulties that used to exacerbate the study of smell (and contributed to its historical neglect) have now turned into a matter of scientific interest. The content of odour perception does not seem straightforward. For example, unlike in visual images, we have difficulties with identifying the single constituents of smell mixtures (an older study by David Laing in 1989 showed that our ability to identify individual components decreases rapidly with mixture complexity). These and many other sensory puzzles spurred recent neuroscientific interest into the nature of smell, and such puzzles resonate with a variety of philosophical questions that have captured my attention.

However, too many misperceptions about smell remain popular. These misperceptions have fostered the long-standing lack of interest in olfaction, especially in the philosophy of mind. One was its persistent image as a ‘lower sense’ that lacks cognitive significance. (Thank you, Enlightenment.) This view has been corrected by the sciences, where many popular opinions about our sense of smell were exposed as misguided. For example, dogs are not necessarily better at tracking smells than humans. Quite the contrary: a now famous study by Noam Sobel tested thirty-two hungry Berkeley undergrads and showed that they can track chocolate in the same way that dogs sniff out pheasants. Our difficulty in assigning names and labelling odours is not a fact about human biology, but simply a result of (modern, Western) cultural neglect. (Of course, you don’t have to take my word for it. Just talk to fragrance chemists. They dazzle you with the richness of their odour language.) Moreover, it turns out that human olfaction is not in evolutionary decline either (as Pinker, Sagan, and many other popular science writers would have you believe). Instead, its significance shifted from orthonasal (inhaling) to retronasal (mouth-breathing) smelling, a process that is fundamental to our refined capacities in flavour perception. The importance of smell in tasting has been emphasized and recently brought to wider attention by neuroscientists such as Gordon Shepherd, as well as philosophers and cognitive scientists such as Barry Smith and Charles Spence.

Meanwhile, a general theory of smell and flavour perception has yet to be established. Flavour has significantly shaped human culture and history, and its multi-dimensional and cross-modal character invites a plethora of philosophical questions about perceptual content and dimensions. In answer to these questions, a better understanding of its neuroscientific basis and current scientific development is essential.

 

Figure 1

 

How do we smell, and how does our brain make sense of the scents in our nose? At first, the olfactory system seems like a straightforward three-level pathway (Figure 1). Odour perception begins when odorants (smelly molecules) are recognized by the olfactory receptors that are situated on the cilia of the olfactory nerves in the nasal epithelium. The receptor signals are collected in spherical neural spheres (so-called glomeruli) in the olfactory bulb at the frontal lobe of the brain (a domain that really looks like a bulb!). Notably, each sensory neuron expresses only one receptor gene (coding for one receptor type), and all neurons expressing a particular receptor are collected in one glomerulus. What you end up with here is a beautiful and neat activation pattern for each odorant—a fingerprint for each smelly molecule in the brain, if you will! This topographic organization of the bulb was expected to be maintained throughout further processing stages in the olfactory cortex. This is how it would work if this were the visual system, and one might reasonably expect it to be the same for olfaction. Now, however, it turns out that the higher-level processing of smells might be organized differently.

The open question is how the brain maps odours as a non-spatial, multidimensional stimulus. This points to an interesting difference with the visual system in its topographic representation of a spatial stimulus. As a cognitive scientist, I do wonder here: What are the implications of a ‘missing’ (or at least hidden) map in the olfactory cortex for our understanding of smell perception? One potential implication is that there may not be a central cortical domain where odour activation signals are synthesized into a unified smell percept. This brings us to something comparable to the so-called binding problem in vision: How does the brain compute a synthesized percept from different and segregated processing domains? To date, this question also remains open. In light of this, olfaction emerged as a new model system for understanding the principles of higher brain organization over the past two decades. Thus, for the philosophy of science, its current dynamics and susceptibility to the revision of its core premises makes olfactory research an excellent example for studying the ambiguity of determining what is a reliable research strategy.

The results of my research are currently being turned into a monograph about olfaction as an emerging model system in neuroscience and for theories of perception. This will address how changes in experimental and cognitive strategies define the meaning of central ideas in olfaction (e.g. olfactory primaries, perceptual dimensions of smell, the olfactory brain). The book will also include a transcribed discussion of key questions in olfactory research based on my interviews with several olfactory researchers. These edited dialogues provide a glimpse behind the scenes of ongoing research and the pluralism of scientific opinion about open questions. It further offers an insight into the kinds of philosophical questions and ideas of interest to practicing scientists. In fact, if we want philosophers of science to successfully exchange with practitioners, it is important that we move beyond the proclamation that has been repeated ad nauseam by some philosophers, namely, that scientists should listen to us. Scientists need not listen to philosophers—they should talk to us (and, that said, we should talk more to them).  

Columbia University

 

Image credit: Tony Alter, 'A Nose for the Road'

 

Scientific explanation from the history and philosophy of science to general philosophy of science (and back again… and again… and again) | Lina Jansson

 

 

Philosophers of science of all stripes draw on the history of science.  However, within philosophy of science there are diverging trends between literature in the history and philosophy of science and the work in (what often goes under the name of) ‘general’ philosophy of science. With the caveat that what follows paints a picture with very broad brushstrokes, the trend among those working on integrated history and philosophy of science is towards recognizing particular differences between scientific fields, periods, and practitioners. On the other hand, the driving motivation in general philosophy of science is towards unified frameworks and theories.

Causation in Scientific Methods | Rani Lill Anjum

 

Need scientists worry about philosophy? Or should philosophers get off their backs and let them do their work in peace? Unsurprisingly, many scientists want to stay clear of philosophical discussions. What is more disturbing is when I hear philosophers themselves announce that our discipline has nothing useful to offer science. In my view, they could not be more wrong.

Aesthetics in Science | Milena Ivanova

 

Aesthetic considerations feature widely in science. Many scientists claim that aesthetic values guide their activities, motivate them to study nature, and even shape their attitude regarding the truth of a theory. Some scientists also regard the product of their intellectual activities, whether scientific theories, models, or mathematical proofs, as works of art. Interestingly, recent studies in neuropsychology have shown that exposure to beautiful equations activates the same area of the brain in mathematicians and scientists as exposure to beautiful pieces of art. How is the concept of beauty understood by scientists; how do they come to regard some features of a theory as aesthetically appealing; and what role can be given to aesthetic considerations in scientific reasoning?

The Limits of the Numerical | Stephen John

 

There are many good reasons to want social policy to be based, where possible, on numerical evidence and indicators. If the data clearly shows that placing babies on their back reduces the risk of cot death, this information should guide the advice which midwives give to new parents. On the other hand, not everything that matters can be measured, and not everything that can be measured matters. The care a midwife offers may be better or worse in ways that cannot be captured by statistical indicators. Furthermore, even when we are measuring something that matters, numbers require interpretation and explanation before they can be used to guide action. It is important to know if neo-natal mortality rates are rising or falling, but the proper interpretation of this data may require subtle analysis. To make matters worse, many actors aren't interested in proper interpretation, but in using the numbers to achieve some other end; as a stick with which to beat the midwifery profession, say.

Anna Alexandrova and I are co-PIs on a project funded by the ISRF and based at Cambridge trying to think through such issues around the ‘Limits of the Numerical’ in the context of healthcare policy. As the sketch above suggests, there are lots of different senses in which the ‘numerical’ might be (or should be) limited: it may be impossible to measure some things accurately; it may be possible, but politically, morally, or socially inadvisable to measure others; some measures may be fine in some contexts but there may be limits to their use in others. Therefore, our team includes expertise not only in philosophy of science, but in political philosophy (Gabriele Badano) and anthropology (Trenholme Junghans). We are also lucky to have sister projects looking at the uses and abuses of numerical indicators in two other domains of social life: climate change policy (based at Chicago), and higher education policy (UCSB).

One reason to explore these topics is their obvious practical relevance; another is more theoretical. The use of numerical indicators is often praised as a way of ensuring that policy is ‘objective’. However, there are at least two senses of ‘objectivity’ at play in such claims: we might think that using numerical indicators, as opposed to human judgement, means policy is more likely to be based on an understanding of the world as it really is. Alternatively, we might think that using numerical indicators is more likely to ensure that policy is not swayed by idiosyncratic interests and biases. These two concerns can come apart: rolling a die to make a treatment decision may ensure that the decision is not swayed by a doctor's interests, but it does not increase our chances of identifying what is, in fact, the ‘best’ treatment. On the other hand, even if relying on trained judgement is more likely to get us to the truth, such reliance may seem to leave us at the mercy of a physician’s whims. Philosophers of science spend a lot of time worrying about whether measurement tools are objective in the sense of mirroring nature; many political debates, however, are more concerned with ensuring that measures are objective in the sense of being fair or impartial. Showing a policy-maker that her shiny new evidence hierarchy is epistemologically flawed may not speak to the reasons she values that tool: that it cannot be ‘gamed’ by big pharma.

 

To make these general comments a bit more concrete, consider a case study that has fascinated our team: the work of the National Institute of Health and Clinical Excellence (NICE) in the UK. Very roughly, NICE’s role is to advise NHS Trusts as to which drugs to buy. As part of this process, NICE (in)famously calculates the amount of health benefit (measured in the metric of Quality Adjusted Life Years, QALYs) that can be expected to result from purchasing a drug. In turn, NICE typically recommends that drugs should not be purchased when they cost more than £30,000/QALY. (Strictly, for the purists, per incremental QALY—but leave that to one side). This ‘threshold’ is, of course, incredibly controversial, because it means that NICE often recommends against buying drugs that would, undoubtedly, benefit some patients, but only at great cost. Where, then, does the number come from?

 

The official justification appeals to the fact that the NHS only has a limited budget, and, as such, every decision to purchase drugs has some opportunity cost; in rough terms, if you are spending more than £30,000 to get one QALY, the money could be spent somewhere else in the system to get more benefit. Of course, this form of reasoning raises deep and important questions in moral and political philosophy. Note, however, that these questions only seem interesting if £30,000/QALY does reflect the ‘true’ opportunity cost. Does it? It seems not. Rather, recent research from health economists implies that the ‘true’ threshold should be much lower—around £13,000/QALY. To put it another way, NICE is green-lighting very many treatments that, given its purported aims, it should not be.

 

This seems to be a scandal! After all, regardless of the ethical questions around health resource allocation, it seems that if (part of) NICE’s job is to allocate resources efficiently, they should do it properly. However, the official response to the studies has been rather surprising. The chief executive of NICE replied by pointing out that reducing the threshold would have a detrimental effect on the UK’s pharmaceutical industry. There is something fascinating about this response. It makes no sense at all if we think that the function of numbers in public life is to try to measure some fact about the world (in this case, the ‘true’ opportunity cost). Consider, however, the other role that numbers play: they provide a kind of stability, allowing different actors—the pharmaceutical industry, patient advocacy groups, and so on—to plan their strategies and policies. Changing the number would be like changing the rules of football halfway through the game. Would it be unfair to do that? This may seem like an odd question to ask, but it’s not clear that we get very far in thinking about numbers and objectivity in policy without understanding that fairness—or at least, the impression of fairness—is, often, a key concern. Oddly, even if the £30,000/QALY threshold is unmoored from reality, it can play this second role, much as the rules of football can be arbitrary but enable fair competition.

 

It would be nice if all good things came together, but they don't. Our research into particular tools in health policy opens up, then, a far larger question for philosophers of science: which forms of objectivity matter?

 

University of Cambridge