Alhassanain(p) Network for Heritage and Islamic Thought

Generating Evidence from Argument Construction

I now consider the situation when we have potential evidence in search of hypotheses. I say "potential" here because we must be able to link information to some hypothesis before we can call itevidence . Charles S. Peirce referred to the imaginative reasoning involved in the generation of hypotheses from our observations asabductive reasoning . From some item of information, or combination of items, we generate a hypothesis to explain the observations we have made. I have often thought that Peirce's  writings on abductive reasoning lead one to conclude that the generation or discovery of a new hypothesis always takes place in one glorious episode of such reasoning. In another work I have identified sixteen species of abductive reasoning that I believe capture more of the complexities of the process of discovery or investigation as it is played out over time[168]. These sixteen species result from four levels of the actual creativity of a hypothesis as identified by Umberto Eco, and Paul Thagard's four classes of matters that are to be abduced. On this view, discovery takes place as we mix together these various species of abductive reasoning with other steps involving inductive and deductive reasoning.

What I wish to show is how Wigmore's methods of argument construction, however cumbersome they might seem, also provide an elegant means for generating new evidence. I consider two cases. First, suppose you have just abductively generated a hypothesis you believe accounts for an observation you have made. In order to convince someone that this hypothesis does in fact account for this observation, you would need to construct an argument showing why this new hypothesis does so. In another case, suppose you have already generated some hypothesis from other observations. But you have a new item of information you are attempting to show is relevant to this hypothesis. In either case, the argument you construct involves further stages of imaginative or inductive reasoning. Recall that the interim probanda that your argument contains, however many of them there are, each represents a source of doubt about some proposition. Each source of doubt represents a new line of evidence you might be able to gather.

As an example, have a look at the chain of reasoning shown in Figure 3. Your argument from evidence E* concerning event E involves sources of doubt about events F and G. You identified these stages of your argument abductively. Thus, in constructing this argument you have identified two new items of evidence that you may be able to gather. You should notice that evidence regarding events F and G would be more direct on hypothesis H than is your evidence about event E. In short, arguments from evidence can allow you to generate additional evidence.

Evidence Marshaling and Discovery

The science of evidence also now includes study of ways in which we organize or marshal our thoughts and our evidence during the process of discovery or investigation. The argument for such study is quite simple. The manner in which we organize or marshal ourexisting thoughts and evidence strongly influences how successful we will be in generatingnew thoughts andnew evidence. Discovery or investigation in any area is a complex activity that unfolds over time. We learn different things at different times and we may begin an episode of discovery with different amounts of information. On some accounts it has been said that most of what discovery involves is using sophisticated methods forsearch [169].  The trouble is that there are so many investigations that begin with our having nothing to search. The problem is unique and there is no background of information relevant to this unique situation. We begin to generate thoughts and evidence by asking questions. It seems that, in any case, the process ofinquiry is at least as important as our methods for search. Studies we have performed on evidence marshaling are designed, in part to stimulate the process of inquiry as we generate hypothese and evidential tests of them.

Professor Peter Tillers [Cardozo School of Law] and I began studies of how we might marshal our thoughts and our evidence during the process of discovery or investigation. In several works we have given an account of a linked network of different marshaling operations[170]. It became quite obvious in the early stages of our research that there will be no single method for evidence marshaling that will satisfy all the intellectual demands placed upon an investigator during the process of discovery. Every episode of discovery is unique and proceeds at a different pace. We learn different things at different times in response to the questions we ask. Our network of marshaling operations consists of five tiers containing 15 different operations[171]. Where one starts using this network depends, in part, on how quickly the pace of discovery proceeds.  One of the marshaling operations has relevance only in the field of law; all the others are relevant to discovery in any context. This system is now being incorporated in the field of intelligence analysis. It forms a major step in our efforts to be  more adept at "connecting the dots".

Mathematics and the Discovery of Evidence

I know that there will be many readers who will never contemplate using any of the formal or mathematical methods I mentioned in Section 4.2.3 for grading and combining the inferential force or weight of evidence. I also anticipate that the methods I have described for inference network construction may not be appealing to everyone. One reason is that such methods rest upon very careful argument construction that is as laborious as it is useful. In might be thought that the only use for probabilistic methods, applied in such study, is to allow the sensitivity analysis I described in which we tell various stories about the inferential force or weight of the evidence we have. But such mathematical analyses can do much more than this.

Well-posed equations for the force or weight of evidence can be especially important during the process of discovery as it proceeds in some inferential problem of interest. What happens is that the equations themselves can suggest questions you can ask that you might never have thought about asking if you had not done this analysis. These questions may suggest new lines of reasoning or interpretations of your evidence and the argument you are constructing. I have found this out myself in many studies I have performed concerning the force or weight of various forms and combinations of evidence. As an example, my identification of the conditions under which testimonial evidence can have more force than knowing for sure that the event testified did indeed occur came as a result of the mathematical analysis I performed[172]. In short, mathematics can have heuristic value in studies of evidence as it has in other areas of science.

4.5 A Stronger Definition of a Science of Evidence

I have now gone to some lengths in my attempt to show that a science of evidence goes well beyond the three weaker definitions of the wordscience as given by the OED. All these three definitions say is that science involves study, in a recognized department of learning, that leads to an organized body of knowledge.  In my account of studies of the properties, uses and discovery of evidence, I have shown how the three concepts that have been associated with science are regular features of such studies: classification, comparison and quantification. In the process, I have attempted to show that studies of evidence involve elements of the two stronger definitions of science given by the OED. Evidence can be systematically classified with respect to the kinds of evidence we encounter, that reliable methods for the discovery of new truths about evidence are possible, and that there are both intellectual and practical ends that are served by systematic studies of evidence.

I have also attempted to go beyond what the OED says scientific activity involves. Theories or hypotheses offered in explanation of phenomena of interest are necessary features of science together with methods for testing these theories or hypotheses. In my account of the three major credentials of evidence [relevance, credibility and inferential force or weight] I have offered alternative theories concerning each of these three credentials. But the testing of these theories or hypotheses will not rest upon conventional empirical tests. For example, we cannot conduct conventional experimental tests of the four views of the inferential weight or force of evidence to see which one is "best". The reason is that each of these four views "resonates" to different attributes of the task of assessing the force or weight of evidence. I have long believed that evidence-based reasoning is far too rich an intellectual activity for us to be able to capture all of this richness in any single axiom-based system any of us is likely to construct. I noted that on some occasions it will be advisable to weigh evidence using more than just one of these views. However, on some occasions we can tell stories based on some of these views and ask: do the stories being told make sense? The testing here seems to be logical rather than empirical in nature.

I have also mentioned the various ways in which mathematics can enter a science of evidence when we consider the task of assessing the force or weight of individual items or masses of items in drawing conclusions. The mathematics for doing so is at hand, whether it will be used in any context is another question. Persons in many disciplines do quite well in expressing the intensity of their beliefs about the force of evidence of interest to them without resorting to specific numerical expressions of such intensity. But, as I have noted, mathematical expressions for the force of evidence have heuristic value in suggesting additional questions we might ask about and of our evidence.

I return briefly to where I started in Section 2.0 with Israel Zangwill and his view that the science of evidence is the "science of science". There I mentioned that others have offered views about what a science of science should involve. I now quote from the biologist Ernst Mayr whose views of a science of science will lead me to matters I will mention in Section 5.0. Mayr said[173]:

Increasingly often one reads references to a 'science of science'. What is meant by this designation? It relates to an evolving discipline that would combine the sociology of science, the history of science, the philosophy of science, and the psychology of science with whatever generalizations one can make about the activities of scientists and about the development and methodology of science. It would also include generalizations on the intellectual growth and style of work of the great leaders of science and, for that matter, also of the great army of other scientists who make contributions to the gradual progress of our knowledge and understanding.

I take no position on the issue of whether a science of evidence is also the science of science, as Zangwill claimed. But it seems that Mayr's comments apply equally well to a science of evidence in emphasizing how many persons and disciplines are naturally involved in it. I now turn to the multidisciplinary and integrated nature of a science of evidence and attempt to answer a question I posed at the outset: Who should care about a science of evidence?

5.0 AN INTEGRATED SCIENCE OF EVIDENCE

I begin with a quotation I have used on other occasions; it comes from the French historian Marc Bloch[174]. Bloch said:

Each science, taken by itself, represents but a fragment of the universal march toward knowledge. …. in order to understand and appreciate one's own methods of investigation, however specialized, it is indispensable to see their connections with all simultaneous tendencies in other fields.

So it is with our march toward a greater knowledge and understanding of evidence. We all make specialized uses of evidence and study it in ways that appeal to us.  But we would be foolish indeed to ignore what others have said about evidence, their experiences with it, and their methods of studying it. Bloch's thoughts are as good as any I can think of to set the stage for my remarks on an integrated science of evidence in which we actively share our thoughts and experiences with evidence, its properties, its uses and its discovery.

In my remarks so far on a science of evidence, I have used thoughts and examples drawn from a wide variety of disciplines. Many of these examples come from areas of research that I have never previously examined and cited as being important in my own previous work. I acknowledged at the outset that I completely agree with William Twining's view that a science of evidence must be multidisciplinary in nature. I begin with Twining's thoughts on this matter and then I will provide what I regard as a model we might follow in our efforts to develop a truly integrated science of evidence.

5.1. The Science of Evidence: A Multidisciplinary Venture

William Twining emphasizes that the study of evidence can involve anyone with an interest in the subject. In a recent work he specifically identifies the study of evidence as being a multidisciplinary subject[175].  Notice that I have not said that Twining refers to this subject as a "science of evidence". In our conversations, Twining has not objected to the termscience in connection with the study of evidence, provided that this word is used in a weak sense. I hope that my arguments in this present paper will persuade William that we are entitled to view a science of evidence in a stronger sense of the wordscience .

I have said on many occasions that the field of law has provided us with the richest legacy of experience and scholarship on evidence of any field known to me. Twining's own contributions form a most important part of this legacy. However, he has been among the first to acknowledge that a rich legacy of experience and scholarship on evidence comes from other disciplines. In the minds of many persons the wordevidence immediately brings the field of law to mind, as if the only persons interested in evidence are those who appear in our courts. This point has also been made by Peter Murphy, another evidence scholar in law. He says[176]

The word 'evidence' is associated more often with lawyers and judicial trials than with any other cross-section of society or form of activity. So it is ironic that the basic questions of what evidence is and what its philosophical and scientific properties are, as opposed to questions of what the law of evidence may be, have received relatively little attention in legal scholarship, and are rarely considered by judges and practitioners.

Murphy's and Twining's point here is that persons in the field of law have as much to learn about evidence from other areas as they can contribute themselves. Twining mentions Jeremy Betham's often-cited statement: "The field of evidence is no other than the field of knowledge"[177]. This encompasses all of us. On another occasion I said that the house of evidence has many mansions and that we should visit as many of these mansions as we can[178].

Twining mentions that the topic of evidence is now a high profile subject and he gives a variety of examples including our work on the Leverhulme project. He further argues that the core of the subject of evidence is inferential reasoning. He states that all disciplines having empirical elements share common problems concerning evidence and inference. He cites, as an example, common evidential and inferential problems encountered in history and law as they are revealed in a recent work[179].  But in a mild criticism of Twining's views about the commonality of evidential and inferential problems across disciplines, Professor Eileen Scallen argues that we would perhaps have more to learn by focusing on differences among disciplines as far as evidential questions they raise[180]. She also argues against Twining's claim that inferential reasoning forms the core of the subject of evidence. She prefers to put evidence in the realm of rhetoric and its importance in advocacy.

So we should all share our thoughts and our experiences with evidence, its properties and its uses as they appear in our own contexts. What prevents us from doing so? There are certainly incentives issues to consider. Why should a sociologist spend time and effort discussing her/his evidential and inferential problems with a historian or a chemist? Some cross-disciplinary interactions may be more interesting and profitable than others. For example, the field of history and sociology are linked in the study of social history[181]. Another reason, I believe, concerns the kinds of evidence encountered in certain disciplines.

I have often noticed that very few persons from the physical sciences have taken an interest in discussions of evidence. William Twining has made this same observation. I think the basic reason is that, for the most part, the only evidence considered in the physical sciences is the tangible evidence I described in Figure 1. Such evidence is usually observed under replicable conditions in which statistical information in the form of relative frequencies of observations can be tabulated and analyzed.

Some years ago, I would also have included engineers in this group of persons basically uninterested in other forms of evidence in the research they perform. But I have now had twenty years of experience teaching about evidence and inference to a large number of students from a very wide array of fields of engineering. They have readily taken an interest in all of the forms and combinations of evidence that I mentioned in Section 4.1. The basic reason is that they are not only interested in the design of systems and the physical environments in which they will operate, but they are also interested in the people who will use these systems or be affected in some way by their use. In fact, the first edition of my work on evidence and probabilistic reasoning was published as part of a series in systems engineering[182].

By what means can we make a science of evidence truly multidisciplinary, or integrative that will include persons who do not always interact and share their experiences with evidence and inference? I think we have a very good model to follow, as I now discuss.

5.2 The Science of Complexity: A Model

Nearly three years ago, when I gave my first talk at UCL, I attempted to find some common ground in the work being proposed for the Leverhulme research by the eleven persons at UCL whose proposals I had seen. The obvious common ground I noted in all of these proposals was the complexity of the processes or situations of interest to these eleven persons, who I am now so pleased to call colleagues and friends. I spent most of my talk discussing how each of these proposals reflects at least one attribute of processes we can say arecomplex .  Where did I find these attributes? The answer is: several years ago, I began to read avidly the increasing number of studies performed by scholars in Santa Fe, New Mexico at theInstitute for Studies in the Science of Complexity . The Santa Fe Institute has a very interesting history and has been quite remarkable in its ability to bring together scholars, from a truly wide assortment of disciplines, who in the past may never have thought about collaborating. Persons actively collaborating at the Santa Fe Institute include those having interests in nearly every area of the physical, behavioral and social sciences imaginable. All appreciate the complexity of the processes they are studying. Several works giving an account of the history of the Santa Fe Institute are available[183].

The best way to sample the flavour of an integrated science of complexity, as it has been studied at the Santa Fe Institute, is to examine the multiple volumes now available in the following series:Proceedings Volumes ,Lectures Volumes ,Lecture Notes Volumes , andReference Volumes . To my knowledge, all are published by Addison-Wesley, New York, NY. I currently have three of the volumes in theProceedings Series and one volume in theLectures Series .  I made extensive use of these works in a paper I wrote on probabilistic reasoning and the science of complexity[184]. There are certainly many attributes of complexity in the evidence-based reasoning tasks we all encounter. But my current interest in complexity as it has been studied at the Santa Fe Institute goes deeper than its obvious relation to a science of evidence.

I have wondered recently what will happen to the efforts of all of us currently involved in various evidence-related research when the Leverhulme and ESRC money runs out. Will we all go our separate ways and never collaborate or interact further in our studies? I hope not. I now entertain a proposal that I ask Phil Dawid to take seriously. Why not have aCenter for the Science of Evidence established at UCL? I can't think of a better place for such a center, and I can't think of a person better able to manage such a center than Phil Dawid. As William Twining notes, the topic of evidence is a currently vibrant one, both in the UK and here in the USA. Given our now expanding legacy of research on evidence and inference in a variety of contexts, we should be able to attract additional funds for such a center, that I believe would be an absolutely unique venture. We will have the experience of the Santa Fe Institute and its many accomplishments to draw upon.

5.3 A Science of Evidence: Who Should Care?

If you are convinced at all by my arguments regarding the existence of a science of evidence, who should care about its existence? And, who would benefit from it? I mentioned at the outset that the remaining burden I have is to be able to answer these questions. I began this final section of my thoughts about a science of evidence with some thoughts from the historian Marc Bloch. He gives us some very good reasons why we should care about an emerging science of evidence and its applications in many contexts. In order to better understand our own evidential and inferential problems, Bloch says it is indispensable that we consider the manner in which others, in different contexts, have thought about these problems. Here is in example I have drawn from theSanta Fe Institute Proceedings Volume XVI . It is entitled: Understanding Complexity in the Prehistoric Southwest . A lingering problem in such study is: what caused thesudden disappearance of Native American cultures, such as the Anasazi, from large and well organized communities they had occupied for centuries? And, what happened to them? Who would have thought that possible answers to such questions would come from the interaction of archaeologists, physicists, economists, and the many others involved in the science of complexity? One of the two co-authors of this volume is a Nobel Laureate in physics named Murray Gell-Mann, one of the founders of the Santa Fe Institute.

Here is a short answer to my question: Who would benefit from there being a science of evidence? We would all benefit from an established science of evidence, provided that we all share our thoughts and experiences with evidence-based reasoning. Earlier I mentioned that one of the most important evidential subtleties is the synergism that can often occur when we consider two or more items of evidence jointly rather than separately or independently. I believe that a science of evidence would promote such synergism on a larger scale. When the ideas of two or more persons having different thoughts and experiences with evidence are combined, the joint ideas resulting from their interaction may well be more defensible and persuasive than they would be in the absence of such interaction. In short, I have no idea how many persons or organizations would benefit from continued work in a science of evidence. But my strong expectation is that the number of persons and organizations would draw upon research on a science of evidence would be very large and would represent interests that would surprise all of us.

6.0 IN CONCLUSION

I have taken on the task of trying to defend the idea of a science of evidence seriously for the major reason that we have obtained a substantial amount of money to study this science and how it might be integrated in beneficial ways. It would be more than embarrassing for us to conclude that there is really no such thing as a "science" of evidence, especially embarrassing to those of us who have signed on to a project having the title: Towards an Integrated Science of Evidence . If we do not think a science of evidence exists, why should we worry about whether it is integrated or not?

But I have had another reason for taking the task of defending the idea of a science of evidence seriously. In my remarks on my standpoint in Section 1.0, I did not mention that I have had another objective, which I have waited until now to acknowledge. I have been honoured and pleased more than I can say at having been made an Honorary Professor of Evidence Science at UCL. If there is no such thing as a science of evidence, I would have to give up this title. But I think I will hold on to this title a bit longer until someone demonstrates that my arguments in favour of there being a science of evidence are not defensible or persuasive.

NOTES