A critical method for understanding the JFK assassination
(January 2001; expanded 19 October 2002)

Need for an objective method for understanding the JFK assassination
    One of the major reasons for all the confusion about the JFK assassination is that its students have seldom approached it with a systematic, objective method. Instead, they have used all sorts of ad hoc procedures that have created nearly as many answers as there are researchers. The only way to escape from this morass is to pay careful attention to methodology and adopt a set of procedures that is as rigorous and reliable as humanly possible. It is amazing, and not a little discouraging, that this has virtually never been done in the JFK assassination. If you have any doubts about these claims, just pick up any book on the subject and see whether the author sets forth in the beginning the standards and procedures to be used. With very, very few exceptions, you will not find any.
    What procedures should we use? There is really no choice here—we should apply the basic procedures of the "scientific method," the most successful method of critical thinking the world has ever known. This is not to say that we should adopt the method wholesale or that we need to become scientists, for the classical scientific method cannot be applied directly to the assassination (as explained below). But its major precepts can, after some modification. The rest of this essay describes the scientific method and shows how it can be generalized into a method of critical thinking that works for just about any area of life. To distinguish it from the classical scientific method, we can call it the "critical method."

What do we mean by the scientific method?
    There is no standard definition of the scientific method. One could say that it begins with empirical data, remains controlled by it, and then uses critical reasoning to draw conclusions, all the while trying to verify and falsify each step of the process. Alternatively, one might say that the scientific method is sound thinking applied to solid data, with results being continually tested and conclusions remaining provisional. Whatever its definition, the scientific method is marked by a strict adherence to observation, objectivity, rationality, testing, and revising.
    Another way to understand the scientific method is to list its characteristics. First and foremost, it is empirical, that is, it is based on observations of the world as it is rather than on speculations about what it might be. In order to minimize errors in these observations, the scientific method is objective, that is, it relies on standardized, reproducible techniques for generating the observations, testing them, and attempting to reproduce them in other laboratories. It is rational as it employs logical thinking and critical reasoning to minimize errors of interpreting the data. Although it is not widely recognized, the scientific method is largely one of trial and error, the most common method used by the practitioner to select explanations (hypotheses) to be tested and refined. Once a hypothesis has been selected, it is tested. It can be verified or, more importantly, falsified. All scientific hypotheses must be falsifiable; any idea or explanation that cannot be falsified is unscientific and therefore basically useless—it should be discarded immediately. By means of such attempted falsification, the scientific method is ultimately self-correcting. Of course, any hypothesis that is falsifiable is also vulnerable. If you are to be a scientist, you must be willing to have your ideas tested rigorously.
    Even after a hypothesis has survived one or more tests, it is still not proven; it is merely retained (as a working hypothesis—see below). It is provisional only. In the words of Sir Karl Popper, scientific knowledge (and indeed all knowledge) is conjectural. (Some people prefer provisional, which means the same thing but sounds softer.) Just as all stars ultimately die, all scientific hypotheses, including our pet creations, are ultimately falsified and discarded. Depressing but true. (Science is a tough business—not for the faint of heart.) Thus the scientific method proves nothing and eventually disproves nearly everything.
    Science and the scientific method are not intuitive, natural, or easy. A recent book by Lewis Wolpert explains to nonscientists why science is so easy to misunderstand: Science seems unnatural because it deals with entirely different realms of nature than the tiny corner of the universe on earth that our brains have been optimized to deal with. So if you are having a hard time understanding scientific ideas or thinking "scientifically," don’t worry. It’s just the way we are built.
    The JFK assassination has much in common with that scientific realm. Just as science deals with a world apart from our daily reality, so does the JFK assassination. This was an extraordinary crime that produced extraordinary effects on our country and on the world. We dare not approach it with the same tools that we use for everyday happenings. It needs to be analyzed much more carefully and rigorously, or else we could easily generate answers that are entirely wrong. For example, consider the common cui bono? (who benefits?) approach that is used so often in crimes. It is useful because many ordinary crimes benefit only a few people, who can then be considered first. But the death of JFK could have benefited so many organizations and individuals that this approach becomes useless, and probably counterproductive as well. In fact, the passage of 39 years has not generated any concrete evidence linking any of those "beneficiaries" to the crime. So much for cui bono.
    It also turns out that there is no single, rigid scientific method that guarantees you to succeed, no "scientific cookbook" with a fixed series of steps to follow. Different branches of science operate in quite different ways. But the hold a basic core of procedures in common: depending on objective observations, generating hypotheses by trial and error (polite terminology for guessing, and sometimes wildly), reasoning rigorously, checking data and ideas fiercely, and continually searching for newer and better explanations for old observations.
    Contrary to what most of have been taught, the scientific method is often biased. For example, the choice of topics to study is commonly constrained by the values of a society as expressed through priorities of its funding agencies. Also, the nature of hypotheses posed by investigators often reflects their individual backgrounds. But biases like this are not always bad. They may even be desirable, as in the case of formulating hypotheses, where one person’s bias may be another’s creativity. The wider the range of hypotheses available to explain observations and challenge established ideas, the better. Fortunately, bias affects only the intermediate steps of science—thanks to the self-correcting nature of science and the uniqueness of the real world, the final results of the scientific process are independent of the path used to derive them.
    Borrowing from the cultural anthropologist Robin Fox, we can say that the scientific method often produces trivial results—dull experiments and resulting data that represent only incremental advances over present knowledge. But that is the price we must pay for a few large advances. If waste, duplication, and incrementalism are required in order to produce a few great experiments, then we are certainly better off with the waste than without the science.

Summary of the basic characteristics of the scientific method
    The basic characteristics of the scientific method can be summarized as follows:

1. Empirical—based on data about the world rather than on speculation.
2. Objective—uses standardized rather than ad hoc procedures.
3. Parsimonious—incorporates only those ideas that are supported by specific positive evidence.
4. Provisional—conclusions are tentative, retained as a working hypothesis, and subject to revision by new evidence.
5. Self-correcting—all conclusions are continually challenged and revised as necessary.

These are the characteristics that we need to build into our critical method.

Is the scientific method perfect?
    No. It is wrong more often than it is right. It can be abused by evil people (the Nazis experimenting on people, for example). It is wasteful each time that it is wrong. It is subject to cultural bias. But it is the best system mankind has yet devised for learning about the regularities of our universe. It works where other systems fail. In the last few hundred years, its successes have been stunning.

Broader than science
    The scientific method is not something foreign to all of us, something that might as well have come from another planet. Rather, it is an extension and refinement of how we operate in our daily lives. Every day we assemble data (observe the world), guess at what they mean (formulate hypotheses), and retain some of the guesses and eliminate others (confirm and falsify hypotheses). The difference is that we don’t do these things as carefully, systematically, and rigorously as scientists do.
    Professionals in other disciplines also use something akin to the scientific method in their work. Read a good history book and see how the writer sifts through huge masses of historical data in search of the true explanations for events big and small. Revisit your favorite detective story and evaluate how the investigator reasons his way ever closer to the final answer. In many detective novels, the hero even creates new experiments to confirm his big hypothesis, as in the final, climactic scenes of a Perry Mason or a Hercule Poirot novel. Or, as Fox says, "The real poet, like any artist, tries all the time to see the general in the particular. In this he is no different from the scientist." Thus the main tenets of the scientific method are shared by all areas of critical thinking.
    On the other hand, there remains something distinctive about the scientific method as practiced by scientists. As Susan Haack as written, "What is distinctive about inquiry in the sciences is, rather: systematic commitment to criticism and testing, and to isolating one variable at a time; experimental contrivance of every kind; instruments of observation from the microscope to the questionnaire; sophisticated techniques of mathematical and statistical modeling; and the engagement, cooperative and competitive, of many persons, within and across generations, in the enterprise of scientific inquiry."

Can we use the scientific method in the JFK assassination?
    Strictly speaking it cannot be, because the assassination of John F. Kennedy was not an experiment that we can study by replicating it or by isolating its variables. We can use most of the rest of the scientific method, though. We can check the available evidence and discard any pieces that are false or unfalsifiable. We can check the current crop of "theories" and discard all that are not falsifiable. We can aggressively take the remaining solid evidence, create a series of explanations from it, discard any that don’t measure up, and keep as a starting point the simplest explanation that remains. We can then test this one, discard it if necessary, and keep going until we have a solid working hypothesis, which we will remember is only provisional. Then we can move on to new chapters in our lives, secure in the understanding that we have done the best possible job on the assassination.
    When we have done all this, we will have approached what Susan Haack calls the "genuine inquirer": "The genuine inquirer, by contrast, wants to get to the truth of the matter that concerns him, whether or not that truth comports with what he believed at the outset of the investigation, and whether or not his acknowledgment of that truth is likely to get him tenure, or make him rich, famous, or popular. He is motivated, therefore, to seek out and assess the worth of evidence and arguments thoroughly and impartially; to acknowledge, to himself as well as to others, where his evidence and arguments seem shakiest and his articulation of the problem vaguest; to go with the evidence even to unpopular conclusions or conclusions that undermine his formerly deeply held convictions; and to welcome someone else’s having found the truth he was seeking." This should be the goal of every one of us.

A critical method for the JFK assassination
    So how, practically speaking, can we reach these lofty plateaus in our study of the JFK assassination? Here is a series of steps that I recommend highly for our critical inquiry. It is not fully original. (Few ideas are!) It can be used just about anywhere. It might be called the critical method for real life. It contains 20 steps, but can be summarized in five or six.

1. Ask a question or pose a problem.
2. List all possible preconceived answers (hypotheses), no matter how bizarre or biased. This step incorporates the "multiple working hypotheses" approach, which is designed to maximize the range of possible explanations considered and minimize early bias toward any particular explanation. (See "Multiple working hypotheses—formal statement" and "Multiple working hypotheses—informal statement.")
3. Assemble all relevant evidence.
4. Divide the evidence into "strong" and "weak," where "strong" means objectively validated (physical evidence that has passed the process described in "A critical method for validating physical evidence"), and "weak" means of a type that cannot be objectively validated (all witness evidence, plus any physical evidence that has not yet been validated). (See "Types of Evidence Useful for Understanding the JFK Assassination")

    Strong evidence only

5. List all possible answers, however unlikely, consistent with the strong evidence.
6. Choose the simplest answer consistent with all the strong evidence. (This step is the application of the famous "Occam’s razor," otherwise known as the Principle of Parsimony. It does not necessarily mean, as many think, that the simplest answer is most likely to be right. Rather, it represents the obligatory starting point, for no meaningful explanation may contain any provision that does not explain something, or "work."). This provisional answer is called the "working hypothesis."
7. Test this working hypothesis rigorously against its consequences (predictions) or against new evidence that arises (often gathered explicitly for the purpose).
8. Consider the working hypothesis proved if it passes all the tests and no other answer is possible. (Uncommon.) Then go to step 12.
9. Retain the working hypothesis if it passes all the tests but other answers are possible. Then go to step 12.
10. Reject the working hypothesis if it fails one or more of the tests. Then choose the next-simplest answer and return to step 7 to test it.
11. Continue cycling through steps 7-10 until you find the simplest hypothesis that survives all the tests. Be your own strongest critic. (If two or more successful hypotheses are equally simple, retain them as advanced multiple working hypotheses.) Then go to step 12.

    Strong and weak evidence (Steps 12 through 19 are only for cases where you wish to or need to add weak evidence to the mix, usually when the strong evidence is insufficient and the weak evidence might open new leads. If you stay with strong evidence only, proceed to step 20.)

12. Add selected weak evidence to the strong evidence. Remember that this will downgrade any resulting answer to "speculative and without logical force."
13. List all possible answers consistent with the strong and weak evidence.
14. Choose the simplest answer consistent with all the evidence.
15. Test this working hypothesis against its consequences (predictions) or against new evidence that arises.
16. Consider the working hypothesis proved if it passes all the tests and no other answer is possible. Go to step 20.
17. Retain the working hypothesis if it passes all the tests but other answers are possible. Go to step 20.
18. Reject the working hypothesis if it fails one or more of the tests. Choose the next-simplest answer and return to step 15 to test it.
19. Continue cycling through steps 15-18 until you find the simplest hypothesis that survives all the tests. (If two or more successful hypotheses are equally simple, retain them as multiple working hypotheses.) Go to step 20.

    Either set of evidence

20. Continue testing the successful hypothesis (or hypotheses) against new evidence as it appears. Status of answer: reliable if from strong evidence only, speculative and unreliable if from strong and weak evidence.

Summary of the critical method

1. Ask a question.
2. List all possible explanations for it.
3. List all evidence relevant to it.
4. Test the explanations against the strong evidence only, starting with the simplest possible explanation and adding complexity only as required by predictions or new evidence.
5. Test against weak evidence if needed to open up new leads, but remember that the answers will be purely speculative.
6. Continue testing against new evidence.

After practicing with this method for a few months, you will become very proficient in it and will be able to apply it to a wide variety of situations in your life.

Importance of working hypotheses
    Working hypotheses are essential to the critical method because they express its tentative, progressive, and self-correcting nature. They mesh with the provisional, or conjectural, theory of knowledge and show how we approach the truth by steps. The idea of entertaining multiple hypotheses in the beginning, which some observers call "multiple working hypotheses," shows the the importance of giving every idea an equal chance. This prevents people from neglecting unpopular ideas. It also prevents bias because it allows, even encourages the the thinker to build in biases at the top and let the self-correcting system take care of them.

Role of emotions
    It is often said that feelings and emotions have no place in critical thinking. That view is incorrect—they are deeply involved and play important roles. For example, they start the enquiry—when we strongly want to know the answer to a pressing question, we are responding to inner feelings and emotions. There is nothing wrong with this. Feelings also drive us to think of every possible hypothesis at the beginning (step 2 above). This is also good. But perhaps the most important role of feelings and emotions is helping us persevere—to not give up until we have done the most we can with the available data.
    But these positive roles for feelings and emotions are one side of the story. The other side—just as important—is that we must keep the feelings in their proper place, and not allow them to spill over into parts of the investigation where they don't belong. The proper place for feelings and emotions in critical thinking is at the beginning, helping to start us off on as broad a footing as possible, and keeping us going through difficult times. Feelings do not belong at the end of the process, however, where the conclusions are drawn and the decisions made. This is the zone of pure reason. We must work hard to keep emotions out of this part. In short, feelings are important in starting us off, but reason finished the job. It requires much self-discipline to follow such different rules at the beginning and the end of of an investigation, but it is crucial.

Legal vs. logical reasoning
    Many people think that the law reasons differently from science or classical critical thinking. To the extent that science and classical thinking engage in absolutes, this may indeed be true. But if one accepts the ideas of conjectural knowledge and working hypotheses, the law is not so different. For example, "finding" someone guilty or not guilty based on probabilities of less than 100% rather resembles choosing a working hypothesis.
    Herbert L. Packer's "A Measure of the Achievement" shows how similar the steps in legal reasoning about the assassination can be to the steps in our critical/scientific approach. He formulated the question, listed the critical physical evidence (and ignored evidence from witnesses), chose a hypothesis, tested it against the physical evidence, sought out other hypotheses consistent with the physical evidence, chose the most reasonable working hypothesis, and considered witness testimony in a corroborative role. We formulate the question, list all possible hypotheses, list all the relevant strong evidence, find all hypotheses consistent with this evidence, choose the simplest of these as our working hypothesis, continue to challenge it with new evidence, and occasionally consider the strongest witness evidence. I submit that these two approaches are essentially identical even though the order of their steps differs slightly. The following table highlights their similarities:

Note how minor the differences are: (1) we list hypotheses before evidence, whereas Packard lists evidence before hypotheses; (2) Packard chooses and tests one hypothesis before trying others, whereas we list and test all hypotheses in a group; (3) we challenge or working hypothesis with new evidence, whereas Packard doesn't.
    In short, the best legal method is virtually the same as the best critical method. This extremely important result implies that there is one best way of working with evidence, and both the law and the classical arts and sciences are using  it. Therefore we must learn to use it fluently if we are to get the right answer for the assassination.