Conspiracy is not a fact Kenneth A. Rahn Center for Atmospheric Chemistry Studies Graduate School of Oceanography University of Rhode Island Narragansett. R.I. 02882-1197 Presented at _The Third Decade_ Second Research Conference Omni Biltmore Hotel, Providence, R.I. 17-20 June 1993 Abstract For a conspiracy to be considered a fact, one or more lines of evidence for it must be proven individually. In practical terms, this means documenting conclusively that the known shooter in the Depository was helped by at least one additional person. Ways to help include planning the assassination, financing it, procuring the weapon(s), preparing for the shooting, the actual shooting (additional shooters or help in the Depository), escaping, or covering up the plot. Available evidence may support but does not prove any of these avenues of conspiracy, save possibly additional shooter(s). The strongest evidence for additional shooters, the backward lurch after the head shot, can be disproven with straightforward physics. The other major lines of evidence for multiple shootersþthe head wound, the body wounds, and the acousticsþcan be similarly shown to be unproven or disproven. Thus conspiracy remains unproven; it is not a fact. But nonconspiracy is also unproven (and unprovable). Is the situation completely indeterminate? Not really, for by comparing the simplicity and adequacy of the conspiracy and nonconspiracy explanations, one can at least rank them. Because the nonconspiracy scenario is simpler and explains more than conspiracy does, nonconspiracy must be chosen before conspiracy. Introduction During the relatively short time that I have been interested in the JFK assassination, I have noticed that discussions of it are frequently ad hoc, that is, that they give minimal attention to logic and procedures. Another way of stating this is that they focus on a specific issue at the expense of the big picture. As a result, discussion and debate commonly lack perspective. I believe that more-careful consideration to logic and procedures can help eliminate these less-important or erroneous ideas at an early stage of discussion, before they can influence our thinking unduly. For example, consider the main tenet of this conference, that conspiracy in the assassination is historical fact. I believe that logic and procedures lead to the opposite conclusion, namely that conspiracy in the JFK assassination has not been shown to be a fact. This paper present the case for this conclusion. Requirements for proving a proposition A proposition can be proven in one of two basic ways: by observing it directly or by inferring it from facts or other propositions. In turn, inference may take one of two forms: deduction or induction. Deduction is the process of inferring a special case from a general principle; induction works in the opposite direction by inferring a general principle from multiple specific cases. Figure 1 shows a simplified view of the relations between observation, inference, deduction, and induction. When it comes to defining þproof,þ we must be more careful, however. In scientific and common usage, þproofþ carries the strong connotation of absoluteness, or conclusive demonstration (100% certainty). If not absolute proof, then as near to it as humanly possible. The law, however, recognizes five levels of _proof,_ graded according to the needs of the type of case being tried. The law rejects absolute proof as being unworkable, though, because no one would ever be convicted if absolute proof were required. Thus, when the law speaks of _proof,_ it nearly always refers to something which is considerably less than absolute. In this paper, we use _proof_ in the absolute sense, and reserve the terms _determine_ and _conclude_ for less-then-certain demonstrations. This corresponds closely to the legal uses of _determine_ and _conclude._ How can something be proven? Figure 1 shows that there are two paths to certainty: observation and deduction. But observation and deduction do not automatically result in proof; either can be inconclusive. For example, the reliability of observation depends on circumstances -- if someone gets a good look at a crime, or photographs it, the observation can be conclusive; if it is dark or the observer only gets a quick glimpse of the perpetrator, the observation may be inconclusive. Deduction can similarly be conclusive if the promises are accurate and the rules of logic are followed, or wrong if these criteria are not met. On the other hand, induction can never be certain, for induction means generalizing from a known part of a group to an unknown part of the group. One can never be sure of the properties of the rest of the group until they are observed. Induction in favorable circumstances can approach proof, but it can never reach it. Unfortunately, however, most new knowledge we gain, most proofs of propositions, and most solutions to daily problems are based on induction rather than deduction. All that knowledge, all those attempted proofs, and all those solutions are consequently uncertain. But how uncertain are they? Can their probabilities be close enough to unity that they are for all intents and purposes conclusive, say 99% or 99.9%? Can the items in question remain uncertain in principle but be proven in practice? Other than in the controlled world of science, where ideas can be refined and tested repeatedly with new data and special experiments, I donþt believe induction can lead to proof. In nearly all real-world circumstances, induction canþt even come close to proof. There are four main reasons why practical inductive answers are so uncertain: small sample sizes, low reliabilities of data, lack of confirmatory experiments, and evidence not corroborating other evidence. Small sample sizes means that few pieces of evidence are available to test the proposition (in life and law, it is common to make do with as few as two or three pieces of evidence). Low reliabilities means that the available pieces of evidence are frequently highly uncertain, i.e., they are not strong evidence. Lack of confirmatory experiments means that after the available evidence is used to generate a first conclusion about the proposition, nothing new is available against which the conclusion can be further tested. The last reason why inductive conclusions are so uncertain is the most important and the hardest to understand: inductive evidence doesnþt corroborate other evidence in the way commonly believed. It is not possible here to give a full proof of this critical preceptþwe can only review the concept of corroborating evidence and point out the weakness in the reasoning behind it. Corroborating evidence is defined as evidence which strengthens and confirms other evidence. The idea is that two pieces of evidence on the same subject are stronger than either alone. For example, if two persons view a crime independently, and each oneþs observation is 60% reliable, their joint reliability is greater than 60%. If enough independent witnesses to the crime can be found, the reliability of their joint testimony can approach 100%. Corroborating evidence doesnþt have to be of the same type as the originalþcombined eyewitness reports and physical clues also qualify. In fact, most corroborating evidence is of a different type from the original evidence. The concept of corroborating evidence does not withstand rigorous scrutiny. A close look into the mathematical basis for corroboration reveals that it starts from inappropriate dataþthe probabilities of various combinations of reports from multiple observers rather than the simple combined reports themselves. To determine the joint reliability of combined evidence, one need only sum the probabilities for and against the event as reported by the various observers, and then divide the sums for and against by the number of observers. This procedure is equivalent to the joint reliability being the arithmetic average of the individual reliabilities. This additive approach can be used whether the witnesses are random or preselected, and whether their reports are representative or skewed toward a particular answer. Most importantly, this understanding of joint reliability eliminates the general notion of corroborating evidence. For example, if two witnesses of 70% reliability view an event and report similarly about it, their joint reliability is still 70%. If they report oppositely about the event, the joint reliability of their testimony is 50% (the average of 70% and 30% for the event). If both witnesses report that the event happened but one is 70% reliable and the other is 90% reliable, the joint reliability that the event happened is 80%. Perhaps the main consequence of joint reliabilities being the average of individual reliabilities is that multiple evidence can never be stronger than its strongest component. Then why bother with weaker evidence? Why not just concentrate on the strongest evidence? Since proving a proposition means reaching 100% reliability, mixtures of evidence of different reliabilities can never prove anythingþonly a single piece of 100% evidence can. Thus, the only real way to prove something is to find one or more pieces of conclusive evidence for itþand forget all the less-reliable evidence. What kind of evidence can be conclusive? Recall from Figure 1 that direct observation or indirect deduction are the only kinds. Indirect induction can never reach 100%. Thus, the only way to prove something is to observe it with 100% reliability or to deduce it as a special case of one or more general principles. How to prove conspiracy in the JFK assassination The statement that þconspiracy is a historical factþ means that conspiracy has been proven. But which kind of þproofþ of conspiracy should we require, the legal kind (<100%) or the absolute kind? I submit that because the assassination is so important to us all, accepting any justification for conspiracy with <100% reliability does everyone a disservice. We should strive for genuine proof wherever possible, and accept nothing less unless completely necessary. At the same time, we should label any aspect of the assassination which is not proven conclusively þprobableþ rather than þproven.þ Nothing is gained in the long run if proof is claimed but only probability can be demonstrated. How then can we check whether conspiracy has been proven? According to Figure 1 and the discussion of corroborating evidence, we must examine individual lines of evidence for proof via direct observation or deduction, but not via induction from smaller pieces of evidence. Before proceeding, we need to define conspiracy and set out the lines of evidence which could establish it. The formal definition of conspiracy is þa secret plot among two or more individuals to perform an illegal act.þ In the case of the Kennedy assassination, a conspiracy would require only that two or more individuals were involved at some stage of the assassination in one or more of the following: planning the act, procuring the weapon(s), preparing for the shooting, shooting, getting away, and/or covering up the plot. Proving a conspiracy thus requires proving that at least two people were involved in at least one of these acts. The participation of the two people must be observed directly or deduced conclusively, not induced. Tests of evidence for conspiracy Many lines of evidence have been proposed for conspiracy. Nearly all are weak, circumstantial (indirect), or negative, and are thus inconclusive. Examples include help in training Oswald, help in exposing the President to danger in Dallas, Oswaldþs borderline marksmanship, his misaligned rifle, the lack of fingerprints on the rifle, lack of time for Oswald to descend to the second floor after the shooting, motives of various public or private groups for having Kennedy killed, Oswaldþs possible intelligence connections, Oswaldþs easy assassination by Jack Ruby, Oswaldþs visit to Mexico City, untimely deaths of potential coconspirators, and governmental withholding of important information from investigative bodies. Each of these lines of evidence is either unproven or sufficiently indirect that proving it would not prove conspiracy. For these reasons, these lines of evidence will not be considered further here. Test of evidence for help in shooting the President The only feasible way to prove a conspiracy seems to be to establish the existence of multiple gunmen. Their locations, identities, and accuracies are secondary to their existence. I consider a rear gunman in the sixth floor of the Depository provenþhe was observed clearly by at least two witnesses. Proving a conspiracy thus requires finding a gunman in the front or another one in the rear. Evidence advanced for a frontal gunman includes eyewitness reports of shots from the grassy knoll, acoustic data for a shot from the grassy knoll, strange activities at the knoll before and after the shots, JFKþs lurch to the rear from the head shot, medical reports from Dallas for frontal wounds to the throat or head, the movement of brain fragments to JFKþs rear, the smell of gunpowder in the motorcade, and suspicious aspects of the Bethesda autopsy. Evidence advanced for an additional shooter from the rear includes refutation of the magic-bullet theory, and the direction of the bullet through JFKþs head. Consider first the evidence for a frontal gunman. Eyewitness reports of shots from the knoll are inconclusive because they are indirect (nobody saw a gunman there), inconsistent (many people didnþt report shots from that direction), and subject to echo effects by the tall buildings on three sides of Dealey Plaza. The acoustic conclusions developed by consultants to the House Select Committee on Assassination were demolished by the National Research Councilþs Committee on Ballistic Acoustics in 1982, on several different grounds ranging from basic to highly mathematical. The strange activities reported at the grassy knoll constitute indirect evidence at best, and are therefore inconclusive. The Dallas medical reports for frontal wounds are either simply wrong (throat) or inconsistent with the autopsy and the mass of other evidence (the head wound), and are therefore invalid. The smell of gunpowder by certain members of the motorcade is highly uncertain evidence because most people didnþt smell it, and even if the reports were true, they would not prove conspiracy because they would not establish who had fired or why. Suspicious aspects of the Bethesda autopsy such as burning of the original draft report or alleged interference with the autopsy are, at best, indirect evidence of conspiracy, and so have limited probative value. Thus we are left with Kennedy's backward lurch and the associated backward movement of some fragments of his skull. Together, these pieces of data are powerful evidence for conspiracy, so much so that we devote the entire next section to dealing with them. But they also fail the test of proof, for solid physical reasons. Now consider the evidence for a second rear gunman. The single-bullet theory, or _magic-bullet_ theory as it is popularly called, has perhaps been discussed more than any other piece of evidence for conspiracy. It thus may come as something of a surprise to recognize that proof of conspiracy based on objections to this scenario is actually very weak. This argument for conspiracy is untenable because it is a negative proposition (there must have been multiple shooters because the body wounds to Kennedy and Connally cannot be explained by a single shooter); negative propositions cannot generally be proven unless some great natural law can be invoked -- not the case here. Thus this evidence for a second rear gunman is invalid. [Of course, failing to disprove the magic-bullet theory does not automatically prove it. But it can be proven by the pattern of wounds in the bodies combined with the number of bullet fragments found in the Presidential limousine.] The direction of the bullet through the Presidentþs head has been claimed to be consistent only with an accidental shot from one of the Secret Service agents in the Presidential follow-up car. Close inspection of this argument reveals that it hinges critically on the extent to which the President was looking to his left when the bullet hit his head. The originator of this argument (Howard Donahue) apparently improperly accounted for the angle of the limousine with respect to Zapruder's camera. When this deviation is added to his equation and Kennedy's angle with respect to the film is estimated properly, the argument collapses. Thus, the available evidence does not prove a second shooter from the rear. Does Kennedy's backward lurch prove conspiracy? I believe that Kennedy's backward lurch constitutes the most-powerful evidence for conspiracy. Visually compelling in its intensity and timing, it would seem to be impregnable proof of a shooter from the front right (near the knoll). But on closer inspection, this argument falls apart -- the lurch actually proves a single shooter from the rear. In brief, here are the reasons. First, Kennedy's head moved forward at the instant of impact, not backward. The existence of a quick forward snap at the moment of impact is evident from the Zapruder film, and is recognized by conspiracists and nonconspiracists alike. It occurred between frames 312 and 313, and amounted to somewhat more than one inch when measured halfway up the back of Kennedyþs head. The backward lurch of Kennedy's head began 1þ3 frames later, depending on whom you believe, and covered 8þ9 inches in total. My measurements of these movements are shown in Figure 2, with the position of the head in frame 312 set equal to zero. The forward snap is not detectable when the film is played at full speedþonly the lurch can be seen. Because the backward lurch began well after the killing bullet left Kennedyþs head, it was not a direct physical impulse from the bullet and therefore cannot be used to determine the direction of the bullet. Nevertheless, its cause is intriguing, even though it does not affect the main argument. Three main causes have been proposed for the lurch, a _jet effect_ reaction to fragments of the head spurting forward, a neuromuscular reaction to the bullet, and a second bullet from the front. A second bullet from the vicinity of the grassy knoll can be rejected for several reasons: no second cloud of fragments (to the rear) was seen, only one set of entrance and exit wounds is found in the head, the left hemisphere of the brain is undamaged, Kennedyþs lurch was a very different kind of movement from the snap, and the bullet didn't have enough energy to create the lurch. The jet effect can also be dismissed because the fragments had too little energy to create the lurch. By contrast, a massive neuromuscular reaction seems consistent with Kennedy's backward motion. Consequently, I believe that this is the correct explanation for the lurch. As opposed to lack of information provided by the backward lurch, the forward snap can be used to determine the direction of the killing bullet. The key is to recognize that the bullet/head collision is actually a three-body collision (bullet, head, fragments), not a two-body collision (bullet and head) as universally proposed to date. Unfortunately for the physical interpretation, the head is the middle body; it can snap forward or backward depending on the final motions of the bullet and fragments. [This can be proven straightforwardly from the laws of conservation of momentum and energy.] Thus, the forward snap of the head is not automatic proof that the bullet came from the rear, as it would be for a two-body collision. The great significance of the forward snap is that it was in the same direction as the movement of the pinkish cloud of fragments seen so clearly in Zapruder frames 313 and 314. Since the cloud and the head effectively represent the entire momentum of the head/body system after the collision (effects of large fragments of skull thrown to the rear are insignificant), and both moved forward, this means that the net momentum transferred to the head/body by the bullet was also in the forward direction, i.e., the killing bullet came from the rear. Now let us consider the energetics of the collision further. Was there enough momentum and energy in the bullet to account for the forward snap of the head? My calculations, summarized in Figure 3, show that there was just enough to account for the velocity that I measured but not enough to account for the higher forward velocity reported by Thompson. In fact, Thompsonþs velocity seems too great to be theoretically possible. Could a bullet from the front have accounted for the backward lurch? As shown in Figure 4, analogous calculations show clearly that it could not have, mainly because all of Kennedyþs upper torso lurched backward, not just his head. His torso actually pulled his head backward, rather than the reverse. Thus, the lurch was an entirely different kind of motion from the snap, and is inconsistent with a bullet. In summary, then, Kennedyþs visually arresting backward lurch is a gigantic red herring. Not only is it no evidence for a frontal shot, but it could not have been caused by a frontal shot. Rather, the quick forward snap, together with the forward motion of the cloud of fragments, proves that the killing bullet came from the rear. Thus, the available evidence does not prove a shooter from the front. This result, combined with the lack of proof for a second shooter from the rear, means that multiple shooters have not been proven. This in turn means that conspiracy has not been proven. Is nonconspiracy proven? But has nonconspiracy been proven? The answer is a clear þno,þ for two reasons. First is the practical impossibility of proving a negative proposition such as þthere was no conspiracy.þ The inability to prove that Oswald was not aided in killing the President does not prove that he acted alone. We will probably never be able to prove the absence of conspiracy. Thus we are left without proving conspiracy or being able to prove nonconspiracy. Conspiracy, which can be proven in principle, hasnþt been, and nonconspiracy canþt be proven in principle. We seem to be left in a totally indeterminate state. Occamþs razor The situation is not as hopeless as it seems. Even though neither explanation is proven, nonconspiracy must be taken before conspiracy if we are forced to choose. According to the time-tested philosophical principle known as Occamþs razor, if two competing scenarios explain a set of observations equally well, the simpler one must be chosen over the more-complex one. This principle ensures that no explanation will contain any useless components. In the case of the assassination, nonconspiracy must be chosen over conspiracy because nonconspiracy is simpler than conspiracy and explains the available evidence as well as nonconspiracy does, and much of it better. Conclusions This review of evidence for conspiracy has resulted in five major conclusions: þ in order to prove conspiracy, at least one line of evidence must prove it individually; weaker evidence cannot be combined into proof þ the proof must be direct observation or deduction, not induction þ no such proof has been shown for conspiracy þ nonconspiracy by its very nature cannot be proven þ if we must choose between conspiracy and nonconspiracy, Occamþs razor requires that nonconspiracy be chosen, because it is simpler and fits the evidence better.