Judgments of Beauty in Theory Evaluation. Devon Brickhouse-Bryson
This transcendental argument will conclude the argument for my thesis. My thesis is that judgments of beauty are part of how we evaluate theories; that a theory’s beauty is part of what makes it good. But there will remain several outstanding issues to be addressed. First, I will have spent some time thinking about the nature of explaining and theorizing, but there is a third related concept worth exploring: understanding. My core claim about explaining and theorizing is that they are necessarily systematic. This fits well with what is usually claimed is the nature of understanding as compared to knowledge: whereas knowledge is propositional, understanding is systematic. It will be important to speak to how my thesis relates to understanding. Second, the arguments I will develop in defense of this thesis are meant to be general and apply to theorizing of all kinds, but I will pay special attention to theorizing in philosophy. But this issue—the role of judgments of beauty in theorizing—is often specifically raised in the context of scientific theorizing. This is because scientific theorizing is supposed to be particularly empiricist or hardnosed; one might think that judgments of beauty can have utterly no place there. It will be important to speak to how my thesis relates to scientific theorizing. Third and finally, Rawls’ work—thinking about what desiderata a theory of justice must satisfy and giving a theory of justice in light of that—is an important foundation of this project. I have generalized Rawls’ attention to the methods of theorizing, including reflective equilibrium. But giving a theory of justice comes with its own special issues: a theory of justice is not merely supposed to explain something; it is supposed to provide a practicable framework for organizing society with an eye to peace, liberty, equality, and stability. It will be important to speak to how my thesis relates to these special issues in political theorizing. Each of these three topics could support a manuscript in their own right, but I will here only begin to explore them and flag them for further work. I will do this in the Coda.
Claiming that judgments of beauty are relevant to theory evaluation—that beauty is connected to truth—inevitably strikes many as wishy-washy or going soft on the hard business of discovering the truth in philosophy or science. But I will dispel that impression and argue that we must rely on our judgments of beauty when evaluating theories for truth. There is another, more ancient adage worth remembering: Pulchritudo splendor veritatis, “Beauty is the splendor of truth.”11 This adage does not say that beauty is truth, nor will I. I do not deny that we should reject a theory, no matter how beautiful, if it is not true. But our task when doing philosophy or science is to figure out which theories are true or otherwise epistemically good. And we don’t have direct access to that truth, antecedent to our judgments of beauty about theories, any more than we have direct access to that truth, antecedent to our judgments about fit with the data. Instead, finding that a theory is beautiful will be an important step toward finding that it is true, in the same way that finding that it fits with the data is an important step toward finding that it is true. A theory can be beautiful and yet not be true, just as a theory can fit with the data and yet not be true. Nevertheless, beauty and fit with the data are connected to truth and we must rely on them when forming our judgments about which theories we have reason to believe are true. Discovering whether a theory is true, which is indeed our ultimate goal, requires discovering whether it has some other property. And I will argue that one such other property, a middle term between theories and truth, is beauty.
NOTES
1 This is obviously meant to echo Rawls’ famous first lines of A Theory of Justice. Although the subject matter of this book is quite different from the questions Rawls addressed in his work, it will be clear that I am deeply indebted to him. I use the word “true” here only to echo Rawls. As I will discuss shortly, I only mean that theories must be principally evaluated according to epistemic values.
2 “Theory” is sometimes a fraught term, but I will be using it here merely to mean a “system of thought that explains some phenomenon.” Note that on this usage of the term systematicity is built into the concept and the purpose of theories is specified as explanation. Notice also that no degree of uncertainty is connoted by the term.
3 There are some debates over the exact nature of the epistemic value of theories. See, for example, Cartwright and McMullin (1984) and Slater (2008). And it is, of course, possible that there is more than one epistemic value that we use to evaluate theories. There is also the classic realist/antirealist dispute about how to understand the truth value of scientific theories. I mean the central claim here—that theories are principally evaluated according to epistemic goods—to be ecumenical with respect to these debates. I will continue to use “truth” as a stand-in for the core epistemic value of theories, but keep in mind that I mean this to be neutral with respect to debates over nature of the epistemic value of theories.
4 The arguments developed in this paragraph against the libertarian, radical egalitarian, and utilitarian theories of justice are, of course, the rudest sketches of arguments. It’s not my purpose here to seriously argue for one theory of justice over any other, we’re merely working through these sketched arguments to illustrate how the methods of theory evaluation we’ve considered work and how they can be deployed alongside one another in an attempt to get to a final answer as to which of the competitor theories is true. Rawls of course goes into much more detail in arguing for his theory. Indeed, he uses a more sophisticated method of theory evaluation—reflective equilibrium—to advance his preferred theory.
5 Fit with the data is closely related to Rawls’ method of theory evaluation, reflective equilibrium. For more on reflective equilibrium, see Brandt (1979), Brink (1987), Daniels (1979, 1980a, 1980b, 1983, 1996), DePaul (1986), Holmgren (1989), Mandle and Reidy (2013), Rawls (1971, 2001), and Sencerz (1986). Coherence is an important part of reflective equilibrium and is also sometimes discussed as method of theory evaluation unto itself. For more on coherence, see Bender (1989), DePaul (1987, 1993), Mackonis (2013), Olsson (2005), Sosa (1980, 1989), Swanton (1992), and Thagard (1993). Reflective equilibrium (and to that extent coherence) is also connected with theory underdetermination and has roots in Quine’s view of theory evaluation. For more on theory underdetermination and the Quinean roots of contemporary reflective equilibrium, see Bergstrom (1984), Boyd (1973), Earman (1993), Glymour (1971), Laudan and Leplin (1991), Quine (1960, 1969, 1975), and Stanford (2013). I will examine reflective equilibrium and coherence in detail in chapter 3.
6 I put “theory” in quotation marks because this probably doesn’t even qualify as a theory since it is not a system of thought, but is instead a mere list of claims.
7 For more on simplicity as a method of theory evaluation, see Baker (2013), Derkse (1993), Sober (1975 and 2015), Swinburne (1997), and Walsh (1979). Simplicity is also often examined in the particular context of scientific theory evaluation. For more on simplicity as it particularly relates to science, see Bunge (1963), Chandrasekhar (1987), Feuer (1957), Forster and Sober (1994), Hillman (1962), Kemeny (1953), and McAllister (1999). For more on explanatory virtues, including but not limited to simplicity and coherence, see Laudan (2004) and Schindler (2018). I will examine simplicity in detail in chapter 4. I suspect that the method of unity—preferring theories that are more unified—is a close cousin of the method of simplicity, though I leave that argument for another time.
8 Copernicus’ theory also involved epicycles and it is not clear from the historical record how many epicycles he added to his theory. But treat this as a thought experiment if you like: Imagine that Ptolemy’s theory did achieve greater fit with the data than Copernicus’, but only by postulating hundreds more epicycles. It would still be evaluated as an epistemically worse theory because of its significant lack of simplicity. I’ll explore this example in more detail in chapter 4.
9 I have focused on simplicity thus far, but this should not be read as giving a privileged place to simplicity. I am not suggesting that simplicity and beauty are identical, nor do I think that all judgments of beauty are judgments of simplicity. But I will argue (mainly in chapter 4) that simplicity is one particular species of beauty (alongside others on this list: coherence, unity, elegance, and so on). That is, simplicity is one type of how a thing can be beautiful. Some have been concerned to argue that judgments of beauty in math and science are not merely judgments of simplicity; see Inglis and Aberdein (2014) and Todd (2008). Such arguments will not be threatening to my view,