Friday, April 23, 2010

What Is Science?

Ian Hacking, who has been interested in the nature and role of experiment in science, once said that science involves (sometimes? always?) "speculation, calculation, and experiment." Representing and Intervening: Introductory Topics in the Philosophy of Natural Science 215 (1983). Ian Hacking has been a student of the history of science, and he has been influenced by the relativizing tendencies of theorists such as Thomas Kuhn. But, he says, he, Hacking, is not a relativist. He might be called -- he has called himself -- a "pragmatic realist."


The dynamic evidence page

It's here: the law of evidence on Spindle Law. See also this post and this post.

Progress(?) in Developing New Course in Scientific & Expert Evidence

Having received a flood of responses :-) to my plea for suggestions about the design of my fall semester course in scientific evidence, I am happy to report I have made some progress -- I think I have made some progress -- in designing the course.

My course is a seminar (I think, but I await word from the administration). My course will cover some of the usual topics -- such as fingerprint evidence, mechanical lie detectors, syndrome evidence, and the like. But my course will not focus on the "technical" aspects of these topics (though it won't ignore them). I will focus on the basic epistemological issues raised by the use of hard science, soft science, and nonscientific expert evidence. (These questions cannot be avoided.)

I have told my students they must pick and discuss two major pieces of literature with different views on some topic. I am suggesting they pick asterisked literature from the following list:

*Ellen Bass & Laura Davis, The Courage to Heal: A Guide for Women Survivors of Child Sexual Abuse (1988); Ellen Bass & Laura Davis, The Courage to Heal: A Guide for Women Survivors of Child Sexual Abuse (4th ed., 2008); Wikipedia Article

*Erica Beecher-Monas, Evaluating Scientific Evidence: An Interdisciplinary Framework for Intellectual Due Process (Cambridge 2007)

*Scott Brewer, "Exemplary Reasoning: Semantics, Pragmatics, and the Rational Force of Legal Argument By Analogy," 109 Harv. L. Rev. 923-1028 (1996)

*Scott Brewer, "Scientific Expert Testimony and Intellectual Due Process, 107 Yale L.J. 1535

*Nancy Cartwright, The Dappled World: A Study of the Boundaries of Science (Cambridge 1999, reprinted 2001 & 2003)

*Susan A. Clancy, The Trauma Myth (Basic Books 2009)

*Martin A. Conway, Recovered Memories and False Memories (Oxford 1997)

*Deidre Dwyer, The Judicial Assessment of Expert Evidence (Cambridge 2008)

*Gerald Edelman, Second Nature: Brain Science amd Human Knowledge (Yale 2006)

*David L. Faigman, Legal Alchemy: The Use and Misuse of Science in the Law (W.H. Freeman & Co. 2009, 2000)

*David L. Faigman, "The Battered Woman Syndrome and Self-Defense: A Legal and Empirical Dissent," 72 Virginia Law Review 619 (1986); David L. Faigman & Amy J. Wright, "The Battered Woman Syndrome in the Age of Science," 39 Arizona Law Review 67 (1997)

*Paul Feyerabend, Against Method (3d edn. 1993)

*James Franklin, What Science Knows and How It Knows It (Encounter Books 2009)

*Michael Friedman, Dynamics of Reason (CSLI 2001)

*Timothy van Gelder, What Is Argument Mapping? (Feb. 17, 2009)

*Alvin I. Goldman, Knowledge in a Social World (Oxford 1999)

*Goodman, Fact, Fiction, and Forecast

*Susan Haack, Defending Science -- within Reason: Bteween Scientism and Cynicism (Prometheus 2003)

*Susan Haack, Deviant Logic, Fuzzy Logic: Beyond the Formalism (Chicago 1974, 1996)

*Ian Hacking, Logic of Statistical Inference (Cambridge 1965, reprinted numerous times)

*Ian Hacking, Representing and Intervening (Cambridge 1983)

*Ian Hacking, Rewriting the Soul: Multiple Personality and the Sciences of Memory (Princeton 1995)

*Ian Hacking, The Social Construction of What? (Harvard 1999)

*Alan Hájek, The reference class problem is your problem too 156 Synthese 563 (2007)

Hanson, Is There Logic of Scientific Discovery? 38 The Australasian Journal of Philosophy 91 (1960)

Hanson, Patterns of Discovery: An Inquiry Into the Conceptual Foundations of Science (Cambridge 1958)

*Peter W. Huber, Galileo's Revenge: Junk Science in the Courtroom (1991 & BasicBooks 1993)

*E.T. Jaynes, Probability Theory: The Logic of Science (Cambridge 2003) (only for people with considerable proficiency in mathematics and probability theory)

Philip Jenkins, Pedophiles and Priests: Anatomy of a Contemporary Crisis (Oxford 1996)

E.D. Klemke, Robert Hollinger & David Rudge with A, David Kline, Introductory Readings in the Philosophy of Science (Prometheus 3d ed., 1998)

Arthur Koestler, The Act of Creation (1964, reprinted 1989)

*Bart Kosko, Fuzzy Thinking: The New Science of Fuzzy Logic (1993)

*Thomas Kuhn, The Structure of Scientific Revolutions (Chicago, 2nd ed. 1969; 3rd ed. 1996)

Imre Lakatos, Proofs and Refutations: The Logic of Mathematical Discovery (Cambridge 1976)

*John Langbein, "The German Advantage in Civil Procedure," .....; Ronald J. Allen, ...

*Elizabeth Loftus & Katherine Ketcham, The Myth of Repressed Memory: False Memories and Allegations of Sexual Abuse (1994, paperback 1996)

*Lorenzo Mangnani, Abduction, Reason, and Science: Processes of Discovery and Explanation (Kluwer 2001)

Grover Maxwell & Robert M. Anderson, Jr., eds., Induction, Probability and Confirmation (University of Minnesota 1975) (vol. VI Minnesota Studies in the Philosophy of Science)

*John Monahan, Laurens Walker & Gregory Mitchell, "Contextual Evidence of Gender Discrimination: The Ascendance of 'Social Frameworks,'" 94 Virginia Law Review 1715 (2008)

*Robert P. Mosteller, "Syndromes and Politics in Criminal Trials and Evidence Law," 46 Duke Law Journal 461 (1996)

*Matteo Motterlini, ed., For and Against Method: Imre Lakatos and Paul Feyerabend (Chicago 1999)

*National Academies of Sciences, Strengthening Forensic Science in the United States: A Path Forward (National Academies Press 2009) (online & free)

*Sidney Perkowitz, Empire of Light: A History of Discovery in Science and Art Chapter 2 (Joseph Henry Press 1996) ("Seeing Light")

*August Piper, Linda Lillevik & Roxanne Kritzer, What's Wrong with Believing in Repression?: A Review for Legal Professionals, 14 Psychology, Public Policy & Law 223 (2008)

*Michael Polanyi, Personal Knowledge: Towards a Post-Critical Philosophy (Chicago 1958, 1962)

*Karl R. Popper, Conjectures and Refutations: The Growth of Scientific Knowledge (Routledge & Kegan 1963, 1965, 1969; reprinted 1974, 1976, 1978, 1984. and 1985; 1989, reprinted 1991 & 1992)

*Karl R. Popper, The Logic of Scientific Discovery (Routledge 1959, 1968, 1972, 1980)

*Karl R. Popper, Realism and the Aim of Science (Routledge 1983, paperback 1985; reprinted 1992 & 1994)

*Dorothy Rabinowitz, No Crueler Tyrannies: Accusation, False Witness, and Other Terrors of Our Times (Wall Street Journal Book, Free Press 2003)

*Mike Redmayne, Expert Evidence and Criminal Justice (Oxford 2001)

*Daniel L. Schachter, The Seven Sins of Memory: How the Mind Forgets and Remembers (Houghton Mifflin 2001)

Tom Siegfried, Odds Are, It's Wrong: Science fails to face the shortcomings of statistics Science News (March 27, 2010)

*Alan Sokal & Jean Bricmont, Fashionable Nonsense: Postmodern Intellectuals' Abuse of Science (Picador 1998)

*David Stove, Scientific Irrationalism: Origins of a Postmodern Cult (Transaction Publishers 2001, paperback 2007)

*D.C. Stove, The Rationality of Induction (1986)

*Peter Tillers, Picturing Infference (2004 & 2005)

Mark Twain, The Tragedy of Pudd'nhead Wilson and the Comedy of Those Extraordinary Twins (1894) (available in numerous reprints)

*United States v. Shonubi, 802 F. Supp. 859 (E.D.N.Y., 1992) (Weinstein, J.) ("Shonubi I"); United States v. Shonubi, 998 F.2d 84 (2d Cir, 1993) (Oakes, Newman & Cardamone, JJ.) ("Shonubi II"); Joint Report (Testimony) of Schum & Tillers (Dec. 21, 1994) in United States v. Shonubi; United States v. Shonubi, 895 F.Supp. 460 (E.D.N.Y.) ("Shonubi III") (Weinstein, J.); United States v. Shonubi ("Shonubi IV"); United States v. Shonubi, 962 F. Supp. 370, 375 (E.D.N.Y. 1997) ("Shonubi V"(!)); Peter Tillers, "Introduction: Three Contributions to Three Important Problems in Evidence Scholarship," 18 Cardozo Law Review 1875 (1997) (draft of pertinent part of article available here); Mark Colyvan, Helen M. Regan & Scott Ferson, "Is It a Crime to Belong to a Reference Class?," in Henry E. Kyburg, Jr. & Maraiam Thalos, eds., Probability Is the Very Guide of Life 331 (2003); Peter Tillers, If Wishes Were Horses: Discursive Comments on Attempts to Prevent Individuals from Being Unfairly Burdened by their Reference Classes 4 Law, Probability and Risk 33 (2005).

*Timothy Williamson, Vagueness (Routledge 1994)

Cf. Edward Levi, Introduction to Legal Reasoning (Chicago 1949 & revised 1962); H.L.A. Hart, The Concept of Law (1961, 2d ed. 1997)


The dynamic evidence page

It's here: the law of evidence on Spindle Law. See also this post and this post.

Tuesday, April 20, 2010

Elements of Legal Claims and Affirmative Defenses

In a comment about L.J. Cohen's conjunction paradox I said:
Footnote: If you believe (as I do) that all probabilities about factual hypotheses are conditional probabilities [e.g., P(element 1| evidence x)], then the product rule, if applied at all, should be applied to such conditional probabilities (and not to freestanding, or unconditional, probabilities [e.g. P(element 1)].
My own comment gave me the following thought(s):

Although the elements of claims or affirmative defenses -- more precisely stated, although the facts that satisfy the elements of legal claims or affirmative defenses -- may be "random variables" in the sense that they can take on various probability values, they are not random variables in the sense in which an evenly balanced die is a random variable.

The probability of an element (or, more precisely stated, the probability of a fact that satisfies an element) is conditional on evidence: i.e., P(Element n|Evidence x) -- or, more precisely stated, P(Fact n| Evidence x). That expression yields a probability: the resulting probability is a function of (i) the prior probability Fact n and, (on a Bayesian view of things), (ii) on the ratio of P(Evidence X|Fact n)/P(Evidence x|~Fact n). The same will be true for every other element of the claim or affirmative defense.

  • Note: Even the "prior probability" Fact n is not "absolute," or unconditional: The prior probability of Fact n is conditional on "background evidence," of evidence that is present, that is there, before Evidence x "comes along," or is considered. See Hajek's convincing argument that all probabilities are conditional probabilities.
  • Is there any reason to assume that the chance of any probability value (between and inclusive of 0 to 1) for some Fact n given some Evidence x is equal to the chances of any other probability value between and inclusive of 0 and 1? I can't think of a valid reason why we should make this assumption. Can you? So a material fact in issue conditional on some evidence is not that sort of random variable: The correct analogue is not the equiprobability that we attach to each of the possible outcomes of an evenly-balanced die or an evenly-balanced roulette wheel, is it?

    If that's correct, just what, precisely, does the expression P(Fact n| Evidence x) represent or "stand for"? If the expression represents someone's epistemic uncertainty, ... whose uncertainty would a numerical value for P of Fact n given Evidence x represent? And once we have an answer to that question, what would our answer imply (if anything) for the chances of success for a proponent of a legal claim or an affirmative defense?

    These are murky waters. Perhaps it is better for me to stay away from them. (I'm no mathematician or logician. I'm just a poor ol' befuddled law teacher.)


    The dynamic evidence page

    It's here: the law of evidence on Spindle Law. See also this post and this post.

    Sunday, April 18, 2010

    My Muddled Musings about L.J. Cohen's Conjunction Paradox

    Is there a paradox -- a meta-paradox? -- about the assumption that the product rule applies to burdens of proof and persuasion on the (multiple) elements of a legal claim? This assumption is the basis of L.J. Cohen's "conjunction paradox." See L.J, Cohen, The Probable and the Provable 58-62 (1977).
    I wrote this -- substantially this -- to a good friend today:
    Assume that legal liability depends on elements a, b, c & d. Assume that these four elements (or, in any event, 3 of these 4 elements) can be classified either as elements of a claim [assume a civil case] or as elements of an affirmative defense. (In theory affirmative defenses could be done away with altogether -- by making all elements elements of claims.)
    Assume that claimant has the burden of persuasion (assume this is defined in terms of probabilities) of slightly more than p(.5) on each element of each claim and that respondent has the burden of persuasion of slightly more than p(.5) on the negation of each element of each affirmative defense.

    If the product rule (not modified for dependencies) applies to legal claims (which are assumed to consist of elements) and also to affirmative defenses (which are also assumed to consist of elements) -- and why should not the product rule apply to affirmative defenses if it applies to claims?--, does it follow that if elements a, b & c rather than just elements a & b are elements of the claim, that the claimant's burden of persuasion for the entire claim (with three elements) is roughly .125 rather than .25 (with two elements) and does it also follow that the respondent's burden (on the entire affirmative defense) rises to roughly .5 (from .25)? Can this (logically) be?

    Look at the problem this way. Assume the claim has two elements a & b. Assume the affirmative defense has elements c & d. If the claimant's burden of persuasion in this situation is _roughly_ .5 on each of the four elements, does it not follow that if an affirmative defense is "in play" (because properly raised by the pleadings or otherwise), the claimant's burden on all four elements -- the conjunction of those four elements -- is roughly .0625 whereas the respondent's burden on the affirmative defense (the conjunction of not-c and not-d) is roughly .25? Is there a paradox here, a paradox about the assumption that the product rule applies here?

    Put it this (equivalent?) way: If the conjunction rule applies and all four elements are elements of the claim (and there is no affirmative defense), the respondent wins if it establishes that the probability of the negation of any one element is roughly (slightly more than) .5. However, if two of the four elements are part of an affirmative defense (and if, therefore, they are not elements of the claim), respondent wins by relying only on a showing of "high" probabilities (a probability slightly greater than .5) of the negation of each of the two elements -- i.e., by showing that the probability of the negation of each element of two elements is slightly more than .5. If so, how can it be (on one horn of the conjunction paradox) that claimant's responsibility is to show (at least) that p(c & d) is roughly .25 whereas respondent must show that the probability of p(~c & ~d) is roughly .25? Doesn't the rule against self-contradiction, or the inverse relationship between the probability of some thing X and the probability of some thing ~X and the convention that probability of some thing X and the probability of the complement of X must sum to one (1) mean that the probability of the subset (c & d) and the probability of the complementary subset (~c & ~d) must equal one? If so, is it logically incoherent, self-contradictory, to assume that the product rule applies to the problem of the burden of persuasion on a claim? (My basic argument remains unchanged if you assume that the burden of persuasion on a claim requires that probability of the entire claim be slightly more than .5 -- and that this means [the other horn of the conjunction paradox] that the probabilities of some elements of a claim must be more than .5, often [depending on the number of elements] much, much more than .5. But I think the counter-riddle I have tried to describe also arises here, though in a somewhat different guise. But don't ask me to explain!)

    N.B. The conjunction paradox does not go away just because alternative factual scenarios (which have facts that instantiate or satisfy an element of a legal claim) can establish a legal claim: The paradox remains. (I once worked this out to my satisfaction. But, again, please don't ask me to do so here.) But my counter-paradox (meta-paradox?) also remains, I think.

    But perhaps my argument (which definitely falls short of a proof!) -- perhaps my argument about the existence of meta-paradox has a logical flaw? It's entirely possible that it does!


    Postscript: As the comments to this post show, my musings (see above) did not lead anywhere. What makes the conjunction paradox so agonizingly difficult is that one has the sense -- or, in any event, I do -- that the proper mathematical interpretation of the burden of persuasion on a claim (or an affirmative defense) is that the jury must be instructed (or the trial court must understand) that it can find for the claimant (or for the respondent on the basis of an affirmative defense) only if it finds (or the judge concludes) that the claimant (or respondent) has established the probability of the claim as a whole (or, in an appropriate situation) the affirmative defense) meets or exceeds the probability required by the applicable burden of persuasion -- and not just that each element of the claim (or affirmative defense) meets or exceeds the requisite probability. The difficulty with this interpretation is twofold: (i) it seems to be inconsistent with the way that the law usually expresses the burden of persuasion and (ii) if each element must be shown to the probability required by the legal burden of persuasion, and if the claim or affirmative defense has more than one element, the application of the product rule says (even when there is some dependence, but less than complete dependence, between the probabilities of the two elements) that the overall claim or affirmative defense must be established to a probability that exceeds the legally-stated burden of persuasion for the claim as a whole -- and, moreover, unless there is a very high degree of dependence among the probabilities of the elements of a claim or affirmative defense, if there are many elements in a claim or affirmative defense, the requisite level of probability for the claim or affirmative defense as a whole is much higher than the legally-stated burden of persuasion (much higher than, e.g., .5 in a civil case, if a probability of slightly more than .5 is the level of probability that must be shown for each element in the usual civil case).

    If that's the case -- if, for example, in the usual civil case the trier of fact should uphold a claim or affirmative defense with numerous elements only if it finds that the probability of the claim or affirmative defense very substantially exceeds .5 -- does it follow that the jury or trial court should almost always find that the claim or an affirmative defense has not been sufficiently established? No, I think that does not follow at all -- because if the claimant or respondent has oodles of powerful evidence to support each element, the jury or the trial court should, of course, find that the claim as a whole [or the affirmative defense] has been sufficiently established, and it probably will do so. The high probability seemingly required for the claim [or affirmative defense] as a whole speaks only [if it does so] to the question of whether an investigation will uncover evidence that sufficiently establishes a claim or an affirmative defense. Moreover, whether an investigation will uncover sufficient evidence of numerous elements of a claim or an affirmative defense depends in part on the characteristics of the part of the world that is being investigated -- and this means it may or may not be very difficult to uncover evidence that will establish all of the various elements to a very high probability. Yes? No?

    The dynamic evidence page
    It's here: the law of evidence on Spindle Law. See also this post and this post.