INDEX

A-evidence, see evidence

Akaike, Hirotugu, 107

Austin, J.L., 192

Bayes' theorem, 98

Bayesian (B-) evidence, 15, 16, 95 upgraded, 38

Brougham, Henry, 3, 23

Brush, Stephen, 52, 210

Cantor, Geoffrey, 213n

Carnap, Rudolf, 102-104, 114n

Cartwright, Nancy, 136n, 253, 259

Causey, Robert, 217n

Chalmers, David, 216, 224-225, 230, 231, 249, 252n

coherence, see Whewell common cause principle, 243, 244 competing hypothesis (explanation) objection, see Mill

consilience, see Whewell content-giving sentence, 185 complete, with respect to a question, 186 correct explanation, see explanation

Dawid, Richard, 35n, 73n, 229n, 235n

Descartes, Rene

on speculation, 10-11, 48

Di Fate, Victor, 148n, 156n

Duhem, Pierre, 4-5, 63, 77, 169, 173-174

Dupre, John, 245n, 259

Earman, John, 244n

Einstein, Albert, 68

on simplicity, 72, 74, 76,

77, 86-87

on speculation, 1, 15n empirical adequacy, 73 ES-evidence, see evidence Everitt, C.W.F., 52n, 210

evidence

A-(Achinsteinian), 17-18, 41-42, 95-96

from authority, 35-39

B-(Bayesian), 15, 16

for conditional existence claims, 205-208

ES-, 17, 197-198

potential, 17

subjective, 18

veridical, 17, 197-198 explanation

completeness in, 256-259 correct, 185-188

deductive model and counterexamples, 189

explanatory connection, 16-17, 184-185

Feyerabend, Paul, 14, 49-50 Fitzpatrick, S., 118n

Friedman, Michael, 229n

Garber, Elizabeth, 52n, 210 Greene, Brian, 135, 219n, 220, 221n, 232n, 249

Harman, Gilbert, 87, 88

Hempel, Carl G., 181, 189, 191 Herschel, John, 213

Hertz, Heinrich, 18n

holism

evidential, 168

justificatory, 196-202 and verified consequences, 202-205

Howard, Don, 72n

inductive argument for simplicity, 91-94

inference to the best explanation, 33-34, 87

Janiak, Andrew, 72n

Kant, I., 229

Kelly, Kevin, 117-118

Kitcher, Philip, 128n

Lange, Marc, 8n

Laudan, Larry

pessimistic induction, 39, 92, 128, 236n

Laughlin, R.B., 237n, 250, 253 Lewis, David, 100n

Lipton, Peter, 33-34, 87-88

Lloyd, Humphrey, 213

Maxwell, James Clerk, xii, 7,

50-65, 182-183,222 exercise in mechanics, 51-54,

140-143, 204-205 physical analogy, 58-62 physical speculation, 54-58 pragmatism, 60-65, 140fli, 258 on theory construction,

211-213

mechanical philosophy, 221-223 meta-inductive evidence,

34, 36-39

Mill, John Stuart

competing hypothesis

(explanation) objection, 126-130, 181-184 particularism, 168-172 on the wave theory of light,

177-179, 204, 207

Morgan, Gregory, 43n

Nagel, 'Thomas, 76, 216, 223-224,

231, 238-240, 249, 251n, 253n Newton, Isaac, xiii, 11, 22, 28,

126, 221

argument for gravity (simplicity based), 143-154

inductivism, 31-32

Newtonian intelligibility, 254-259

Newton's Rules, 71-72, 126, 144 pragmatic interpretation of Newton's Rules, 160-167

on simplicity, 71-72, 74-75, 85n on speculation, 1, 10-11, 47-49 Norton, John, 156n

only-game-in-town

evidence, 34-39 Oppenheim, Paul, 217n

particularism

and A-evidence, 193-195

evidential, 168 pessimistic induction, see Laudan Pines, David, 237n, 250, 253 Popper, Karl, 12-13, 50 potential evidence, see evidence Powell, Baden, 213 Prigogine, I., 250 probability

likelihood, 98

objective epistemic, 16 posterior, 98 prior, 98

Putnam, Hilary, 217n

Quine, WV, 169, 172

Railton, Peter, 228 Reichenbach, Hans, 113-117, 243 Roche, Michael, 108n Rynasiewicz, Robert, 243n

Salmon, Wesley, 228 scientific spec, 45 simplicity

“aim of science” claim, 77, 133, 135

Einstein on, 72, 74-75 epistemological claim,

73-75, 88-118

as an epistemic strategy, 113-118

globalist view, 84ff

inductive argument for, 91-94 localist view, 83ff

Newton on, 71-72, 74-75 ontological claim, 71-72, 80ff pragmatic, 79-80, 139-143 presupposition claim, 76-77, 133-135

scientific virtue claim, 78, 135, 138 Smolin, Lee, 219-220, 232, 233n, 240-241, 245

Sober, Elliott, 85n, 104-109

Spec, 20 speculation, see spec

pragmatic view (see Maxwell) scientific, 40-46

three contrasting views (very conservative, moderate, very liberal), 10-15, 46-50

truth-irrelevant, 8 truth-relevant, 7, 19-24

Stanford, P.

theorizing conditions, 6-7 theory evaluation

either/or, 209-210

nuanced, 210-215

Theory of Everything (TOE)

a priori strategies for constructing a TOE, 248-250 empirical argument strategies, 246-248

historical argument, 234-237 presupposition argument, 238-240

Theory of Everything (cont.) unification argument, 240-245 what is a TOE?, 216-217, 226-231

why should we want a TOE?, 250-255

Thomson, J.J., 18n, 96-97

Thomson, William (Lord

Kelvin), 4, 63 truth-relevant speculation, see speculation

underdetermination, 75-76, 123-132

van Fraassen, Bas, 73, 78-79, 244n veridical evidence, see evidence wave theory of light, 203-204 and the ether, 176-179

Weinberg, Steven, 6, 228-229, 232n, 235, 236, 249, 251n,252n

Westfall, R.S., 223n

Whewell, William, xii-xiii, 12, 13, 89-90, 169

coherence, 32, 131, 231 and the competing hypothesis objection, 182

consilience, 32, 131, 231 holism, 174-175 hypothetico-deductivism, 32-33 wave Theory, 177-179

Young, Thomas, 3

The conflicting views I have in mind are very conservative, moderate, and very liberal.

a. Very Conservative

The idea can be simply expressed: “don't speculate.” I will take this to mean: Don't introduce an assumption into a sci­entific investigation, with the idea that it is or might be true or close to it, if you don't know that there is evidence for it. Earlier we saw such a view expressed in Brougham's response to Thomas Young's speculations about light. Let me mention two other scientists who express this idea as part of their gen­eral scientific methodology: Descartes and Newton, both of whom demand certainty when assumptions are introduced in scientific investigations.

In his Rule 3 of “Rules for the Direction of the Mind,” Descartes writes, “we ought to investigate what we can clearly and evidently intuit or deduce with certainty, and not what other people have thought or what we ourselves conjecture. For knowledge can be obtained in no other way.”¹⁰ He continues: those who, “on the basis of prob­able conjectures venture also to make assertions on ob­scure matters about which nothing is known,... gradually

10. Reprinted in Peter Achinstein, ed., Science Rules (Baltimore: Johns Hopkins University Press, 2004), 19.

14. Paul Feyerabend, “Against Method: Outline of an Anarchistic ’lheory of Knowledge,” reprinted in part in Achinstein, Science Rules, 377.

16. Many of those who write about evidence use the letter h for “hypoth­esis.” I will do so, too, but will also use the terms “hypothesis” and “as­sumption” interchangeably, and h for both.

20. In 1883, Heinrich Hertz performed experiments on cathode rays in which he attempted to deflect them electrically. He was unable to do so, and concluded that they are not charged. Fourteen years later, J. J. Thomson claimed that Hertz’s experiments were flawed because the air in the cathode tube used was not sufficiently evacuated, thus blocking any electrical effects. In Thomson’s experiments when greater evacua­tion was achieved, electrical effects were demonstrated. Hertz’s experi­mental results constituted his subjective evidence that cathode rays are not charged.

31. Richard Dawid defends versions of views 4 and 5, but not 6. On his versions, evidence is not evidence for the truth, or even for the empirical adequacy of a hypothesis, but for what he calls its “viability.” A hypoth­esis is viable relative to a given field, and to certain types of experiments that can be performed within that field, if it predicts the results of those experiments. He claims that with his restricted sense of evidence, meta- inductive evidence and “only-game-in-town” evidence can provide ev­idence for “viability.” Among the meta-inductive cases he has in mind are ones where the theory was the “only game in town.” If such theories have tended to be “viable,” then this fact counts as evidence for the via­bility of the particular “only-game-in-town” theory. Richard Dawid, “The Significance of Non-Empirical Confirmation,” in Why Trust a Theory? ed. Richard Dawid (Cambridge: Cambridge University Press, in press).

36. Larry Laudan, “A Confutation of Convergent Realism,” Philosophy of Science 48 (March 1981): 19-49.

43. This, of course, leaves open the question of what makes an investiga­tion a “scientific” one—a topic long debated. What I am saying is that how­ever this is to be understood, whether or not an assumption introduced in such an investigation is a speculation depends on whether or not the speculator knows that explanatory evidence for it exists.

44. To be sure, a subjectivist about evidence could adopt Newtonian or Whewellian ideas by saying that e is evidence for him, but not nec­essarily for others, if and only if e and h satisfy Newtonian inductivism or Whewellian consilience and coherence. But this is not the position of Newton or Whewell. Their concepts of evidence are not tied to individuals.

13. Van Fraassen, 'the Scientific Image, 87.

14. In chapter 5, I will examine the very idea of a TOE.

19. Harman, “Inference to the Best Explanation,” 89.

21. Whewell, Philosophy of the Inductive Sciences, chap. 5, reprinted in Achinstein, Science Rules, 162-63.

12. Whether such a theory could actually be used is another matter, which will be discussed in chapter 5,.

14. Victor Di Fate stresses this in his excellent chapter, “Achinstein's Newtonian Empiricism,” in Philosophy of Science Matters: The Philosophy of Peter Achinstein, ed. Gregory J. Morgan (New York: Oxford University Press, 2011), 44-58.

Finally, I return to Newton's rules and offer a pragmatic in­terpretation of them that avoids treating them as rules based on the assumption that nature is simple, or that simplicity provides an epistemic basis for believing in the truth or em­pirical adequacy of a theory. It is not my claim that Newton himself understood the rules in this way. But I believe that, understood in the manner I will suggest, the rules are rea­sonable ones and reflect many, though by no means all, of Newton's ideas.

I will understand the rules not as rules of inference but as rules of strategy that tell you how to go about defending a causal law.¹⁹ Newton's stated aim in the Principia is to “dis­cover the forces of nature from the phenomena of motions and then to demonstrate the other phenomena from these forces.” 'this aim has two parts, first to discover the forces from observed phenomena, and second to show how these forces can be used to explain other phenomena. The first part Newton calls “analysis,” the second, “synthesis.” The rules are rules of strategy for accomplishing the first part. Before

19. See Achinstein, Evidence and Method, 66-78.

Quine's pithy summary of the doctrine is well known: “our statements about the external world face the tribunal of sense experience not individually but only as a corporate body.”^{* 7}

7. Quine, “Two Dogmas of Empiricism,” 41.

The debate between holists and particularists is not a purely philosophical one bereft of practical consequences for scien­tific activity.

10. For a summary of a few basic assumptions of this theory, see chapter 1, section 1.

The definition of “correct explanation” just introduced avoids standard causal counterexamples to deductive models of ex­planation. Here is an intervening cause counterexample, which I introduced many years ago.^{* 17} Suppose Alice ate a

17. Achinstein, Nature of Explanation, chap. 5.

18. J. L. Austin, How to do 'I kings with Words (Oxford: Oxford University Press, 1962). For my own account of the speech act of explaining, see Achinstein, Nature of Explanation, chap. 2.

In evaluating a theory, both sides focus entirely on ep- istemic virtues. Even there, the main focus is on the ques­tion: Has the theory as a whole been “proved,” or at least has evidence sufficient to believe the theory been supplied? Newton, Mill, and Whewell all seem to assume that epi- stemic evaluations are the only ones that are important, and that among such evaluations, the ones to focus on are those that tell us whether there is evidence sufficient to prove or demonstrate the high probability of the theory as a whole. This is an assumption underlying Newton's four rules, Mill's “deductive method,” and Whewell's ideas of consilience and coherence. To be sure, Mill and Whewell, at least, allow the additional epistemic question: Has enough information been provided to make it reasonable to conclude that the theory is a possibility worth considering?²⁴ Newton does not seem

23. “Unofficially,” as I noted in chapter 1, Newton violates this official methodology in his Opticks, as well as in the Principia.

24. Mill suggests that this is so in the case of the wave theory, since it satisfies the “ratiocination” and “verification” conditions of his “deductive

17.

18. I am not here taking sides on the question of whether theories exist in­dependently of us, or whether we construct them. I want to formulate what I say so that both “constructivists” and “realists” about theory-existence can put aside their differences in order to deal with the questions I am raising. Constructivists might understand the question “Does a theory of everything exist?” modally as “Is a theory of everything construct- ible?” Nor will I take a position on the ontological status of theories—e.g., whether they are to be construed as ordered sets of propositions, or as sets of structures, or something else. The TOE theorists I am concerned with offer no views on this issue.

25. Chalmers, e.g., allows different “scrutability” bases, so for him whether laws and entities cited are “final” depends on which base is selected. Greene (Elegant Universe, 16) is somewhat vague on this issue, saying that a TOE is a “theory that underlies all others, one that does not require or even allow for a deeper explanatory base.”

29. See Smolin, Trouble with Physics, and Weinberg, To Explain the World.

Smolin puts this argument for a TOE as follows:

The mind calls out for a third theory [beyond general rela­tivity and quantum theory] to unify all of physics. And for a simple reason. Nature is in an obvious sense “unified.” The uni­verse we find ourselves in is interconnected, in that everything interacts with everything else. There is no way we can have two theories of nature covering different phenomena, as if one had nothing to do with the other. Any claim for a final theory must be a complete theory of nature. It must encompass all we know.³⁷

Smolin has in mind the fact that the four basic forces in physics interact (electromagnetic, gravitational, and strong and weak nuclear forces). Nagel, who has a similar idea, focuses on the fact that the mind interacts with the body.

37. Smolin, Trouble with Physics, 4-5.

46. Greene, denying that it is an a priori metaphysical claim, says that it is possible that certain features of the universe are what they are by chance or divine choice. (See earlier quote in chapter 3, p. 135.) Weinberg (Dreams of a final 'Theory, 54) says that his claim that a reductive TOE exists is “a state­ment of the order of nature, which I think is simply true.” But he offers no defense. Chalmers doesn't argue that a TOE must or does exist, but seems to take the line that it would be a good thing if it did (a position I examine in section 7).

Earlier, I spoke of seventeenth-century mechanical philos­ophy, represented by Newtonian physics, as an example of a (potential) TOE. But now we need to think more carefully about the idea of “everything” in a TOE. It is true that in his preface to Principia, Newton states his aim very boldly and generally as one of discovering the forces of nature from the motions of bodies and then of explaining celestial and other phenomena on the basis of these forces. But in fact the only force he is really concerned with is gravity (he mentions electrical forces, friction, and forces of repulsion, but does­n't work anything out). He is uncertain as to whether there are atoms (i.e., fundamental, indivisible bodies).⁵⁸ Nor, as noted earlier, does he think it is possible to determine from his theory (or from any other mechanical one) what causes the planets to orbit in the same direction on the same plane.

Most important, the theory Newton presents does not answer the question “Why do bodies attract each other in accordance with the law of gravity?”—a question Newton explicitly raises but says that he cannot answer and that he will not “feign hypotheses” to try to do so: “It is enough” (satis est), says Newton, “that gravity really exists and acts according to the laws that we have set forth and is sufficient to explain all the motions of the heavenly bodies and of our

58. Newton, Principia, 795-96.