«by Jonathon Hricko A dissertation submitted to Johns Hopkins University in conformity with the requirements for the degree of Doctor of Philosophy ...»
A DEFENSE OF THE SUPPOSITIONALIST VIEW OF HYPOTHETICAL ENTITIES
A dissertation submitted to Johns Hopkins University in conformity with the requirements
for the degree of Doctor of Philosophy
When scientists put forward hypotheses, they sometimes involve new kinds of entities,
which we can call ‘hypothetical entities.’ Hypothetical entities are pervasive in the sciences,
and some examples include caloric and, up until very recently, the Higgs boson. Some hypothetical entities are discovered, as was the case with the Higgs boson, while scientists conclude that others, like caloric, do not exist. Hypothetical entities pose a number of important challenges for the philosophy of science, and my goal is to develop and defend what I will call the suppositionalist view of hypothetical entities. In chapter 1, I examine the extant views of hypothetical entities, which I draw from the scientiﬁc realism debate.
I argue that these views are all committed to the claim that terms for hypothetical entities putatively refer to empirical entities. In chapter 2, I develop the suppositionalist view of hypothetical entities. On this view, terms for hypothetical entities refer to what are called ‘objects of supposition.’ Examples of such objects from other domains include ﬁctional characters like Superman and mathematical objects like the natural numbers. I draw from analogies with ﬁction and mathematics in order to develop the suppositionalist view in the scientiﬁc domain. In chapter 3, I give a history of a hypothetical entity that I will later use as a test case for views of hypothetical entities. In the late-eighteenth century, Antoine Lavoisier hypothesized that muriatic acid is composed of oxygen and a hypothetical entity ii
ABSTRACTcalled the ‘muriatic radical.’ In the early-nineteenth century, Humphry Davy’s work on muriatic acid showed that it is actually composed of hydrogen and chlorine, and so muriatic acid is hydrochloric acid. Finally, in chapter 4, I use the history of the muriatic radical in order to argue against the extant views, and for the suppositionalist view. I argue that the former are committed to giving a history of the muriatic radical that is either whiggish or incomplete. The latter, however, can give us a non-whiggish history that is more complete, and hence it is preferable to the extant views.
Dissertation Committee Members: Robert Rynasiewicz (advisor), Steven Gross, Yitzhak Melamed, Wilda Anderson, Kyle Rawlins iii
Two people stand out in my mind as playing a crucial role in my development as a philosopher. They are Rob Rynasiewicz and John Waterman. You are the people most responsible for shaping my views in philosophy, and so I’d like to begin by thanking you for this, and for all of your help and support.
Without my family and friends, I wouldn’t have been able to ﬁnish this dissertation. An account of all of the ways in which you’ve helped me would most likely match the length of my dissertation. I thank all of you for your support and encouragement. I owe special thanks to Dan Hricko, Lee Hricko, Matthew Hricko, and Chitra Venkataramani.
I’d like to thank the following people for valuable feedback on the various papers, presentations, and chapter drafts that led to this dissertation: Marianna Bergamaschi-Ganapini, Justin Bledin, Nick Goldberg, Steven Gross, Genco Guralp, Derek Leben, Jeff Maynes, Bryan Miller, Rob Rynasiewicz, Shane Steinert-Threlkeld, Nicholas Tebben, John Waterman, and Karen Yan.
I’d also like to thank the administrative staff of the philosophy department for all of their help and hard work. Alicia Burley and Leslie Bean have made the department a great place to work, and I owe my thanks to Veronica Feldkircher-Reed for her help with all of the challenges involved in scheduling my defense.
Lastly, I’d like to thank my wife, Karen Yan. My time in graduate school would have been worth it even if I ended up leaving without my Ph.D., because that’s when I met you.
This was by far the best thing to happen to me. Moreover, there’s a good chance that I would have left graduate school without my Ph.D. had I not met you. I thank you for your love and encouragement, and I want you to know that you’ve done more than anyone else to motivate me to ﬁnish this dissertation.
1.4 Constructive Empiricism and Hypothetical Entities............. 37 1.4.1 Empirical Adequacy, Observability, and the Semantic View..... 39
4.5.2 The Actual and Counterfactual Histories and the Appropriation Model291 4.5.3 Suppositionalism, Whig History, and Incomplete History...... 297
4.1 A diagram of the actual and counterfactual histories of the muriatic radical... 263
4.2 Vindicated and discredited theories, and their relation to the world........ 293
1.1 INTRODUCTION When scientists put forward hypotheses, they are usually loath to propose new kinds of entities that would inﬂate the ontologies of their theories. But sometimes their hypotheses do introduce such entities, and some of these entities are what I will call ‘hypothetical entities.’ My aim in this chapter is to discuss the extant views of hypothetical entities that are at least implicit in the main positions that occupy the position space of the scientiﬁc realism debate. To that end, I will begin by circumscribing the phenomenon of interest, namely, hypothetical entities in the sciences. If, as I claim, there are some extant views of hypothetical entities, there must be some phenomenon that all of these views are views of, even if it’s the case that they differ in what they have to say about this phenomenon. I will then go through a selective survey of the scientiﬁc realism debate, in which I will focus on three main positions in the philosophy of science, namely, scientiﬁc realism, constructive empiricism, and structural realism.1 I will spell out the view of hypothetical entities that each position is committed to. Philosophers of science haven’t exactly framed their discussions 1 Henceforth, ‘realism’ should be understood as ‘scientiﬁc realism.’ Whenever I have in mind another kind of realism, I will specify this.
in terms of the notion of ‘hypothetical entity’ that will be my focus here. In that case, it will be important to be clear about this notion and any points of contact with the literature, and it will take some work to extract the extant views of hypothetical entities from the above-mentioned positions.
The upshot of this selective survey is that one of the ways in which philosophers of science have attempted to distance themselves from logical positivism is by committing themselves to some variant of the realistic interpretation of the language of science. In short, the basic idea is that theoretical terms are to be understood as putatively referring expressions that have putative reference to empirical entities. A fortiori for theoretical terms used to introduce hypothetical entities into scientiﬁc discourse. In this chapter, I will argue that the commitment to realistic interpretation is widespread. In the remainder of the dissertation, I will argue that this widespread commitment is a mistake, at least when it comes to terms used to introduce hypothetical entities, and I will develop an alternative view of hypothetical entities to put in its place.
1.2 HYPOTHETICAL ENTITIES Hypothetical entities are ubiquitous in science, and perhaps the best way to introduce them is to give a few examples. Towards the end of the eighteenth century, Antoine Lavoisier hypothesized the existence of a simple substance called ‘caloric,’ which he thought to be the matter of heat. In the mid-nineteenth century, John Adams and Urbain Le Verrier hypothesized the existence of an undiscovered planet. It would not be long before astronomers on the continent observed Neptune through their telescopes. As I write this
sentence, the status of the Higgs boson is hypothetical, but it is hoped that the Large Hadron Collider will change this status.2 Caloric, Adams’ and Le Verrier’s undiscovered planet, and the Higgs boson are all examples of hypothetical entities. The examples could be multiplied, and I will discuss more examples later, but these should sufﬁce for introducing the phenomenon of interest.
The term ‘hypothetical entity’ is not new to the philosophy of science. Philosophers mostly use the term as a synonym for ‘theoretical entity,’ as David Lewis does when he claims that “[t]heoretical entities might better be called (as they sometimes are called) hypothetical entities” (Lewis (1970), 428).3 As the above-mentioned examples may already suggest, I mean something different by ‘hypothetical entity’—something that makes it differ in meaning from ‘theoretical entity.’ In order to make this clear, I will ﬁrst have to be a bit clearer about what I take a hypothetical entity to be.
1.2.1 THE ROUGH GUIDE I don’t propose to give necessary and jointly sufﬁcient conditions for what makes an entity hypothetical, but I do believe that the following rough guide captures the basic idea.
A hypothetical entity is a new (kind of) purported entity that a scientist puts forward as a (kind of) purported empirical entity in advance of decisive empirical reasons to do so.4 2 And,indeed, it has.
3 Emphasisis the author’s unless otherwise noted.
4 This rough guide is roughly in agreement with what Rynasiewicz, Steinert-Threlkeld, and Suri (2010) mean by ‘hypothetical entity.’
Terms introduced to name hypothetical entities are what I will call HE terms, short for hypothetical entity terms.
The rough guide that I’ve put forward can be used to circumscribe a phenomenon of interest, namely, hypothetical entities in the sciences. But in order for this to be the case, the rough guide must be at least somewhat “theory-neutral,” in the sense that it is minimal enough to be agreed upon by philosophers involved in the realism debate who may disagree about much else.
As we’ll see, there’s a sense in which the rough guide cannot be accepted as-is by all parties. A philosopher may have to understand it in a speciﬁc way so as to make it square with various other beliefs and commitments. There will therefore be a number of different ways of understanding the rough guide. But this is the sense in which the guide is rough— it offers a starting point to circumscribe the phenomenon of interest. The different ways of understanding are the beginnings of offering a speciﬁc view of hypothetical entities, but there needn’t be any incommensurability among these views if the rough guide can be used to make a speciﬁc phenomenon salient. That said, the rough guide is still in need of some clariﬁcation, and I will provide some of that right now.
First of all, I use the word ‘entity’ in a broad sense, to cover things, individuals, objects, substances, events, processes, properties, and relations.5 In this case, the rough guide can be used by philosophers who do not admit one or more of these into their ontologies. My examples of hypothetical entities are perhaps most easily classiﬁed as (kinds of) things, individuals, objects, or substances, and this will be my primary focus. But the rough guide 5 For an example of this broad sense of ‘entity,’ see van Fraassen (1980), 15.
itself is more comprehensive.
Secondly, a hypothetical entity is a purported entity, since, after all, it’s hypothetical.
But not all purported entities are hypothetical entities. For example, Jack the Ripper is a purported entity. He is an entity, since he is an individual person, and he is a purported entity because it’s possible that more than one person committed the murders in question.
But he is not a hypothetical entity, in the sense that I’m concerned with, because it wasn’t scientists who put him forward as a purported empirical entity.
Thirdly, when a scientist “puts forward” a hypothetical entity, she does so in print or in speech. For example, when Lavoisier puts forward caloric as a hypothetical entity in his Elements of Chemistry, he is concerned to explain various changes in state that occur at
different degrees of heat. He writes:
It is difﬁcult to comprehend these phenomena, without admitting them as the effects of a real and material substance, or a very subtile ﬂuid, which, insinuating itself between the particles of bodies, separates them from each other.
(Lavoisier (1802), 52) He “allow[s] that the existence of this ﬂuid may be hypothetical,” and claims that, “strictly speaking, we are not obliged to suppose this to be a real substance” (Lavoisier (1802), 52, 53). Nonetheless, he his collaborators “have distinguished the cause of heat, or that exquisitely elastic ﬂuid which produces it, by the term caloric” (Lavoisier (1802), 53). This example illustrates some more general points about the act of putting forward a hypothetical entity. Scientists usually do this in order to explain some set of phenomena. And Lavoisier’s
rather tentative attitude towards caloric shows that putting forward a hypothetical entity does not entail that the scientist believes that that entity exists, though she may certainly believe this. The rough guide therefore emphasizes the act of putting forward, and not the beliefs of the scientist.
Fourthly, I enclose “kind of” in parentheses because there are times when scientists hypothesize kinds (e.g., the electron) and times when they don’t (e.g., Adams and Le Verrier’s planet). I use the term ‘kind’ so as not to commit to the existence of natural kinds—the kinds referenced in the rough guide may be natural kinds, but they needn’t be.
Fifthly, by ‘empirical entity’ I have in mind an entity that exists in the natural world.
This rules out