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Published online by Cambridge University Press: 18 September 2019
Few have given an extended treatment of the non-statistical sense of normality: a sense captured in sentences like “dogs have four legs,” or “hammers normally have metal heads,” or “it is normal for badgers to take dust baths.” The most direct extant treatment is Bernhard Nickel's Between Logic and the World, where he claims that the normal or characteristic for a kind is what we can explain by appeal to the right sorts of explanations. Just which explanatory strategies can ground normalities, though, is difficult to determine without inviting circularity into the account. After raising this and other worries for Nickel's account, I develop my own account according to which normal features are those which are explained by the kind of thing involved.
Versions of this paper were presented at the Berkeley-Stanford-Davis Graduate Conference, a session at the 2019 Eastern APA, and a meeting of the UCLA Albritton Society. I am grateful to the participants for their critical engagement. Thanks also to Calvin Normore, Gavin Lawrence, Sheldon Smith, Joshua Armstrong, and Katie Elliot for their commentary on drafts at various stages.
1 Martin Smith has directly discussed this sort of normality at length in ‘Ceteris paribus conditionals and comparative normalcy’, Journal of Philosophical Logic, 36, no. 1 (2007), 97–121; ‘Justification, Normalcy and Evidential Probability’, manuscript; ‘What Else Justification Could Be’, Nous 44, no. 1 (2010), 10–31; and ‘Knowledge, Justification and Normative Coincidence’, Philosophy and Phenomenological Research 89, no. 2 (2014), 273–295. Direct discussions also appear in (among some others): Alexander, Peter, ‘Normality’, Philosophy 48, no. 184 (1973), 137–151CrossRefGoogle Scholar; Millikan, Ruth Garret, Language, Thought and Other Biological Categories (Cambridge, MA: MIT Press, 1984)Google Scholar; Pietroski, Paul and Rey, Georges, ‘When other things aren't equal: Saving ceteris paribus laws from vacuity’, British Journal for the Philosophy of Science, 46, no. 1 (1995), 81–110CrossRefGoogle Scholar; Leplin, Jarett, A Theory of Epistemic Justification (Springer Science & Business Media, 2009)Google Scholar; Yalcin, Seth, ‘Modalities of Normality’ in Charlow, Nate and Chrisman, Matthew, eds., Deontic Modality (Oxford, Oxford University Press, 2014), 230–255Google Scholar; and Schurz, Gerhard in ‘Pietroski and Rey on ceteris paribus laws’, British Journal for the Philosophy of Science 52, no. 2 (2001), 359–370CrossRefGoogle Scholar; ‘What Is `Normal’? An Evolution-Theoretic Foundation for Normic Laws and Their Relation to Statistical Normality’, Philosophy of Science 68, no. 4 (2001), 476–497; ‘Ceteris Paribus Laws: Classification and Deconstruction’, Erkenntnis 57, no. 3 (2009), 351–372; ‘Normic Laws, Non-Monotonic Reasoning, and the Unity of Science’ in S. Rhaman, J. Symons, D. M. Gabbay, & J. P. van Bendegem (Eds.), Logic, Epistemology, and the Unity of Science (Dordrecht, Holland: Springer Science & Business Media, 2009), 181–211.
2 Between Logic and the World: An Integrated Theory of Generics (Oxford: Oxford University Press UK, 2016).
3 When I use ‘kind’ throughout the discussion, it will stand in for ‘kind or individual through time’.
4 In other non-rival formulations, the normal is that which is included in being a kind of thing, or that which doesn't call for an explanation, or doesn't need a special explanation.
5 Echoing Aquinas’ Commentary on Aristotle's Metaphysics VI 2.1174, where he interprets Aristotle's Metaphysics E 2.1026a 33-1027a 28; and also Aquinas’ Summa Contra Gentiles 3.97.8: ‘For since each thing acts on account of its form, so does it suffer passion and is it moved on account of its matter.’ (my translation).
6 Note that in grouping these claims together, we're not claiming that they are transmutable salva inferential profile. We might expect that adding or removing a ‘normally’ might alter the inferential profile of a claim. Consider the case of transmuting from ‘we meet at Joe's on Friday for breakfast’, which can be used to set a policy for the future; and ‘we normally meet at Joe's on Friday for breakfast’, which it seems cannot. Ströβner, Corina, in her ‘Normality and Majority: Towards a Statistical Understanding of Normality Statements’, Erkenntnis 80, no. 4 (2015), 793–809CrossRefGoogle Scholar, supposes that there is a distinct logic to normality laws of the form ‘k’s normally φ’ when compared with normality claims of the form ‘it is normal for k’s to φ’. I am hoping to do something a bit more general here in that I want to understand what judgments intuitively involving non-statistical normality have in common and so Ströβner's project is too narrow for my purposes.
7 How do we in a principled and/or pretheoretical way work out the generics we intend to give an account for? Well, I won't decide in advance. Instead, I'll focus on some paradigm examples and decide ‘a posteriori’ how far this account will go in giving a semantics for generics. There are certain cases, most famously ‘mosquitos carry the West Nile Virus’, that make me think it won't (and perhaps shouldn't) cover every true generic.
8 Some deny that normality enters at the level of truth-conditional semantics or anything resembling it. Instead, Veltman and Bastiaanse in their ‘Making the right exceptions’, Artificial Intelligence 238 (2016), 96–116, among others, argue that normality should be understood in terms of inference rules which don't have truth or falsity, but instead only have some form of validity or invalidity. There is, on this view, no truth-conditional semantics for phrases containing or making implicit reference to the concept of normality. I disagree: I think normality judgments are truth or false and that we can at least develop some heuristics for knowing when they are true or false. One reason to reject the inference rule interpretation is that there is no clear way to handle normality judgments embedded within other normality judgments (or perhaps embedded within any judgment at all)—discussed in Krifka, Manfred, Pelletier, Francis Jeffry, Carlson, Greg, Meulen, Alice Ter, Chierchia, Genaro, and Link, Godehard, ‘Genericity: An introduction’, in Carlson, Greg and Pelletier, Francis Jeffry, Eds., The Generic Book (Chicago: University of Chicago Press, 1995), 1–124Google Scholar.
9 Other plausible types of normality judgment are reliability claims, powers ascriptions, competence or capacity ascriptions, intention ascriptions, causal claims, etc.
10 I've opted for compressed examples here in the interest of space. One shouldn't read anything into this choice.
11 Thanks to Sheldon Smith (Personal Correspondence) for the note that what others call ‘exceptions’ aren't in fact exceptions but would be exceptions if the generalization in question were a universal claim; they are merely apparent exceptions. We can call an exception that truly undercuts a generic or normality claim a real exception.
12 The question of what sorts of exceptions make trouble for normality judgments is a question worthy of its own treatment. For an extended discussion of related issues, cf. Leslie, Sarah-Jane, ‘Generics and the Structure of the Mind’, Philosophical Perspectives 21 (2007), 375–405CrossRefGoogle Scholar; and ‘Generics: Cognition and Acquisition’, Philosophical Review 117 (2008), 1–49.
13 The truth of individual dispositionals like ‘My computer turns on when I press this button’ seem to be grounded in the truth of the corresponding kind-level dispositional – (5) in this case. This individual claim generalizes over cases of pushing that button on my computer, whereas (5) generalizes over all computers (and perhaps all pushings of computer ‘on’ buttons). So the truth of the example in this footnote should be somewhat insensitive to particular button pushings and the truth of (5) should be somewhat insensitive to particular computers (and perhaps their button pushings). This is just what we find: my computer can fail to turn on in a great many cases because I forget to charge the battery and it still be the case that my computer turns on when I push the on button. For (5), even a large amount of button pushings, even over a long period of time, might not interfere with the truth of the judgment. Similarly, a great many computers can fail to turn on when their ‘on’ buttons are pushed – after all, it’s likely that most computers in the world are broken or in a junk yard – and yet (5) will still be true.
14 There are also ‘contrary normalities’, which are cases where many different contrary outcomes are nevertheless normal. For now, we'll simply note that the discussion is riding rough shod over some intricacies. Later on, I will call these ‘incomplete normalities’ to contrast them with ‘complete normalities’ – normalities governing outcomes that have no competing alternative normal outcomes.
15 I use the words ‘outcome’ and ‘feature’ to stand in for features, relations, activities or behaviors, and conditions. I am weary of the philosophical baggage attached to ‘property’, though I'm not sure anything is strictly lost by interpreting me to mean ‘property’ by these words.
16 As a bandage, I can offer the intuition that it would be quite odd if the conceptual space were divided into the, I take it, clearly unified statistical/frequency judgments, the similarly unified nomic judgments, and then a grab bag of judgments with no unity or even family resemblance that nevertheless share features like insensitivity and tolerance if not some version of normativity.
17 Alternatively, we might think this question should be stated as ‘why is it normal for bald eagles to fly?’
18 Nickel defends such a view at great length in the following: ‘Generics and the ways of normality’, Linguistics and Philosophy 31:6 (2008), 629–648; Ceteris Paribus Laws: Generics and Natural Kinds, Philosophers’ Imprint 10:6 (2010), 1–25; ‘Generically free choice’, Linguistics and Philosophy 33:6 (2010), 479–512; ‘The Role of Kinds in the Semantics of Ceteris Paribus Laws’, Erkenntnis 79 (2014), 1729–1744; and Between Logic and the World: An Integrated Theory of Generics (Oxford: Oxford University Press, 2016).
19 Gerhard Schurz, ‘What is Normal?’, appears to hold this view, though his target class of normality judgments is slightly different in that he is only interested in complete normality judgments. Cf. Nickel, Between Logic and the World, 180, and 180 n.3 for critical discussion thereof.
20 This is something close to Millikan's view in Language, Thought, and Other Biological Categories. Understanding exactly what she means by ‘Normal’, though, is frustrated by the lack of a direct analysis or treatment of the concept itself. The central clue on which I'm basing my interpretation is the following passage, in which she offers a preamble to her definition of proper function. ‘Where m is a member of a reproductively established family R and R has the reproductively established or Normal character C, m has the function F as a direct proper function iff…’ (Ibid., 28, emphasis mine). If we attend to the italicized phrase, it appears that she is claiming that reproductively established and Normal are more-or-less interchangeable when it comes to the character of a family. A character is a set of properties had in common by all members of a reproductively established family that were produced normally (Ibid., 25).[20] So a normal character is a reproductively established set of properties held in common in the first order case, and in the higher-order cases it is a set of properties got through normal production of members of the higher-order family. A normal feature, therefore, is a feature got as a result of one's reproductive ontogeny that has been established historically within a reproductive family.
21 Note that ideal is still somewhat ambiguous between different sorts of idealization. This ambiguity comes into view throughout the literature on ceteris paribus laws. For a sampling of different potential interpretations, see Spohn, Wolfgang, ‘Ceteris paribus’, Erkenntnis 57 (2002), 354CrossRefGoogle Scholar, and also Schurz, ‘Ceteris Paribus Laws’, for helpful surveys; Ceteris Absentibus comes from Joseph, Geoffrey, ‘The many sciences and the one world’, Journal of Philosophy 77:12 (1980), 777CrossRefGoogle Scholar; ‘minutis rectis’ comes from Fenton-Glynn, Luke, ‘Ceteris Paribus Laws and Minutis Rectis Laws’, Philosophy and Phenomenological Research 93:2 (2016), 274–305CrossRefGoogle Scholar; though Cartwright, Nancy, How the Laws of Physics Lie (Oxford: Oxford University Press, 1983)CrossRefGoogle Scholar argues for a similar interpretation of many ceteris paribus laws.
22 Clark, Romane, ‘Prima facie generalizations’, in Pearce, G. & Maynard, P. (Eds.), Conceptual Change (Dordrecht, Holland: D. Reidel, 1973)Google Scholar gives voice to something like the view above, though not in these words.
23 Similarity is often defined in terms of distance in multi-dimensional space, where each dimension defining the space is a particular determinable like ‘size’ or ‘limb count’ or the like. The closer an individual is to the prototype, the more prototypical and hence more normal one is. Cf. Neumann, Peter G., ‘An attribute frequency model for the abstraction of prototypes’, Memory & Cognition 2:2 (1974), 241–248CrossRefGoogle ScholarPubMed.; Rosch, Eleanor, ‘Natural Categories’, Cognitive Psychology 4 (1973), 328–350CrossRefGoogle Scholar; ‘Principles of Categorization’, in E. Rosch & B. B. Lloyd (Eds.), Cognition and Categorization (Hillsdale: Lawrence Erlbaum Associates, 1978), 27–48; Rosch, Eleanor, Mervis, Carolyn B., ‘Family resemblances: Studies in the internal structure of categories’, Cognitive Psychology 7:4 (1975), 573–605CrossRefGoogle Scholar; and Rosch, Eleanor, Simpson, Carol, & Miller, R. Scott, ‘Structural bases of typicality effects’, Journal of Experimental Psychology: Human Perception and Performance 2:4, (1976), 491–502Google Scholar.
24 Nickel thinks that generics are existential quantifications over ways of being normal in a respect, where ways are contrary, but each normal, characteristics one can have (determinants of the determinable ‘respect’). Particular hair colors is an example of a way of being normal – humans are normally blonde, normally brown-haired, normally red-haired, etc. Respects are dimensions – like hair color – within which one or more value is normal for a kind and others are abnormal (respects are ‘determinables’). Reproductive method is one respect of being normal in that there are different ways to reproduce – internal gestation and live birth, egg-laying, etc. – and different species have different normal ways of giving birth. So, to say that ‘ducks lay eggs’ is to say ‘there is a way of being a normal duck with respect to reproduction and that way is to lay eggs’. I like Nickel's analysis of generics and think it's the most promising account available. I simply take issue with Nickel's account of normality.
25 Nickel calls it ‘genericity’, following much of the literature on generics, but as far as I can tell normality and genericity are the same phenomenon.
26 Strevens—in, Michael ‘Ceteris paribus hedges: Causal voodoo that works’, Journal of Philosophy 109 (2012)Google Scholar—also explores causal mechanisms as underwriters of defeasible regularities. In that respect, his discussion is similar to Nickel's: both see the defeasibility of causal mechanisms as the source of the defeasibility of certain types of normalities.
27 See Nickel, Between Logic and the World, 178–196 for a full discussion of the definition of characteristicness in terms of explanatory strategies.
28 It's worth noting another difference between our accounts. Whereas Nickel is primarily interested in defining what it means to be a normal k with respect to a property (P-Normality), I am more interested in defining the normal properties or features. This doesn't amount to a substantive difference, but merely a difference in emphasis.
29 This does constitute Nickel's metaphysical account of genericity, which one wouldn't be entirely mistaken to think is – if not the same as – at least closely related to non-statistical normality.
30 Cf. Jennifer Huizen, ‘Rare albino raven murdered’, Audubon (2015, July), retrieved from https://www.audubon.org/news/rare-albino-raven-murdered
31 N.B. that some polymorphisms are caused by environmental cues alone, but we can safely ignore these cases and restrict our focus on the genetically-determined polymorphisms.
32 Assent to this seems to be a necessary precondition to theorizing about non-statistical normality and so is perfectly neutral between accounts of normality. Either way, I think at least Nickel would agree with this minimal characterization.
33 See Cohen, Ariel, ‘Generics, Frequency Adverbs, and Probability’, Linguistics and Philosophy 22 (1999), 221–253CrossRefGoogle Scholar for a sophisticated attempt. Cf. Ströβner, op. cit. as well.
34 The converse is also true: there is no normality if there are no kinds. I think most would agree with this assessment.
35 More broadly, I'm tempted to think that our conception of normality should illuminate what biologists are up to rather than the other way around, but one can see the merits in thinking the reverse. Note that biology will be one way we answer questions about what is normal for a given species, and why a property is normal for a given species, but I don't expect it to also play a role in our conception of what it is to be normal.
36 It is interesting to note that we often use phrases like ‘he's always in his office at 2pm’ to express a normality judgment. We clearly, when pressed, don't mean such statements as universal statements – even with a suitably restricted domain that rules out weekends and work holidays – since we are likely well aware that Dev is sometimes sick or on vacation or at the birth of his child on work days.
37 Aristotle offers the somewhat unhelpful example of citing the fact that an octave in music is a numerical relation in order to explain certain facts about octaves. This is far from the most helpful example available. (Physics II 3, 194b24)
38 Furthermore, certain facts about me obtain because I am who I am and not because of some accidental fact about me – like my running into a table and scarring my brow. For instance, it seems true that I pursued a PhD in Philosophy because that's the kind of person I am or because I am Me and not someone else.
39 How can a necessary feature be nevertheless normal? Well, remember that the distinction between necessities and normalities qua types of relations between kinds and features
40 Is a racoon stumbling upon a squirrel's nut cache a racoon finding treasure? I'm not so sure. What I am sure of is that if I say, ‘treasure was discovered in my back yard’, one won't immediately think of squirrels but will instead normally think of human contexts.
41 Both examples and the overall thought thanks to Gavin Lawrence.
42 Cf. for example, Van Fraassen, Bas, ‘The Pragmatics of Explanation’, American Philosophical Quarterly 14:2 (1977), 143–150Google Scholar; and ‘The Pragmatic Theory of Explanation’, The Scientific Image 5 (1980), 97–157 for a discussion of the contrastive nature of causation and therefore likely of explanation in general.
43 Whereas Van Fraassen (‘The pragmatic Theory of Explanation’) thinks that an explanation is an answer to a why-question and that's all, I am skeptical of such a view. Explanations are answers to why-questions, but perhaps they are other things as well (relations between facts, for instance).
44 There seem to be many examples of properties which are neither normal nor abnormal. Cambridge properties seem mostly to be neutral with respect to normality, as is the property of painting one's skin green – it's not a normal thing to do, but it's too strong to say that it's abnormal.
45 Thanks to Katrina Elliot for raising these worries.
46 Some normalities – ‘complete normalities’ – are such that they will obtain absent interference, while others – ‘incomplete normalities’ – are such that if they obtain they will be normal, but there is no reason to think they will in fact obtain unless we have more information than the kind for which they are normal. The normative inferential profile can in principle only apply to complete normalities. There is no normative pressure toward the obtaining of an incomplete normality: a cat can be calico, black, white, or orange tabby without anything going wrong. In fact, those are all normal outcomes. So to make an inference to a ‘should’ claim about an individual from an incomplete normality judgment would be an error in reasoning.
