The UFO phenomenon, shrouded in mystery throughout the modern era of American science — and still today — has received mixed treatments from historians of science.

The spectrum among objective historians to write on the subject has generally been characterized on one side by the view that UFOs may constitute an anomalous phenomenon — a position that suggests the possibility of the extraterrestrial hypothesis of UFOs, which seeks to explain UFOs as extraterrestrial crafts — and on the other side by the contention that all UFO cases can be explained prosaically in terms of conventional science.

This historiographical analysis will focus primarily on three historical accounts of the modern UFO phenomenon as it pertains to American science: UFOs and the Limits of Science (1981) by Ronald D. Story, The UFO Controversy in America (1975) by David Michael Jacobs, and UFOs Explained (1974) by Philip J. Klass. Each analysis inevitably deals with some recurring themes: the limits of science in satisfactorily resolving questions of the nature and origin of UFOs, the effects of the biases of contemporary scientists for or against the extraterrestrial hypothesis, and the epistemological implications of attempting to study potentially anomalous phenomena on the basis of data that is virtually unusable according to established scientific standards.

Ronald D. Story in UFOs and the Limits of Science (1981) presents a comprehensive analysis of the scientific study of UFOs in order to illustrate the limited state of our scientific knowledge of the UFO phenomenon. He provides a description of biblical and other ancient accounts of UFOs and the 1896-97 waves of airship sightings in America, and then accounts in detail the modern era of the UFO controversy in America — from sightings of mysterious "foo-fighters" by American pilots in WWII to the University of Colorado study led by Edward U. Condon. The author notes that upon assessment of the modern era of the UFO controversy that the spectrum of opinion among both experts and laypeople is incredibly wide and that science has failed to answer not only the extraterrestrial hypothesis, but also whether or not the study of UFOs can produce previously undiscovered scientific knowledge.

Story presents a comparative analysis of the least reliable UFO cases — those based on weak evidence and hoaxes — against the most reliable UFO cases — those that in his opinion remain unexplained and hint at anomalous sources — because "in order to survive the same kind of close scrutiny as given those cases you will see debunked, the evidence given of 'genuine' UFOs must be quite strong indeed." Noting the elusive nature of physical evidence in UFO cases, the author categorically rules out particularly unreliable types of cases — for example, those whose details indicate discrepancies indicative of hoaxes or those in which witness credibility is a question. Story goes on to analyze cases that include photographic evidence of UFOs — some of which he finds persuasive in terms of substance and reliability, noting in several cases that contextual inconsistencies indicative of frauds could not be found by expert photographic analysts.

The author provides incredibly detailed accounts of a category he deems the ten best UFO cases — those that he believes should be considered paramount in terms of reliability and of content suggestive of an anomalous source of the UFO phenomenon. His historical approach here serves as a response to Philip J. Klass's contention that "if the strongest UFO cases can be successfully debunked, then there is very little reason to suppose that any of the less reliable cases go very far in establishing the existence of a truly anomalous phenomenon." Story contends here that the strongest UFO cases have yet to be satisfactorily explained or debunked. His criteria for the strength of evidence in these cases includes the presence of multiple witnesses, above average witness credibility, above average documentation, suggested anomalies that are incompatible with any known phenomenon, and the lack of any reasonable and well demonstrated alternative explanation. Story notes in each case the inability of modern science to explain the UFO phenomenon in prosaic terms.

The author makes conclusions about several aspects of the UFO controversy — each of which points to the limited scope of our scientific knowledge of UFOs and therefore to the question of whether or not scientists ought to be in a position of authority regarding questions of the nature of UFOs. Due to the generally loose application of patterns to the UFO phenomenon — shapes, colors, behavior, and other characteristics of UFOs — and the related issue of often not knowing which UFO samples can be considered valid, Story argues that extreme caution must be taken in assigning importance to patterns among UFO cases. In looking at the most popular theories that attempt to explain the UFO phenomenon — most of which operate on unscientific foundations — Story contends that theories on the nature and origin of UFOs, because they cannot be scientifically studied or established, should be considered philosophic rather than scientific inquiries. In response to claims that UFO cases can be explained prosaically solely on the basis of the unreliability of human observation, Story argues from a strictly logical standpoint that the entire population of UFO witnesses cannot be deemed unreliable solely on the basis of other witnesses' past mistaken observations.

Still, the author asserts that the burden of proof for the UFO phenomenon lies with UFO proponents; as they advocate the existence and study of a new phenomenon, it is their responsibility to use established methods to provide proof. However, Story suggests that the question as to which methods should be considered established or capable of such study may not be so clear cut. Firstly, the UFO phenomenon does not lend itself to analysis by scientific means. Secondly, the practitioners of science — subject to social-psychological factors that create prejudiced attitudes against unconventional topics — are no less biased or emotional than the average person. For Story, "Scientists are accustomed to basing their theories and conclusions on what they call 'facts'" — but within the UFO controversy, there has been little done among both UFO proponents and skeptics to scrutinize the basis for pertinent facts. The limitations on the part of science to properly address the UFO phenomenon, then, put the subject directly within the expertise of philosophers of science — far better equipped than scientists, in Story's view, to address the methodological and epistemological aspects of the phenomenon.

Story raises several astute points regarding the limitations of science in definitively solving questions of the nature and origin of UFOs. The informal and non-reproducible character UFO data — clearly outside of the methodological scope of established science — coupled with the potential biases of scientists against particular topics, as indicated historically by nineteenth-century scientists' biases against the notion of meteorites, certainly implies a context in which both scientists and historians of science must tread carefully in attempting to establish conclusive knowledge. Perhaps Story's greatest accomplishment here is to demonstrate just how little we know about the UFO phenomenon — and thus how cautiously we must approach attempts to definitively explain it.

David Michael Jacobs in The UFO Controversy in America (1975) provides an account of the modern UFO phenomenon in American history with emphasis on the institutional and societal responses to the phenomenon. Beginning with the waves of airship sightings in 1896-97, the author presents a vast chronological and non-technical history of UFOs in America — much of which comes from newspaper and magazine articles written for popular consumption. Focusing not on the technical and scientific aspects of the UFO phenomenon but rather on the sociological and political implications of the controversy surrounding it, Jacobs describes in detail the most controversial chapters — such as the Air Force's inquiries into UFOs, the activities of NICAP and other civilian groups that threatened the Air Force's monopoly on the study of UFOs, and the Condon Study. In an attempt to explain why such large amounts of time and effort have gone into study of the mystery behind UFOs, Jacobs outlines the approaches of the main groups within the modern UFO controversy — namely, the Air Force, the scientific community, and private civilian-level UFO organizations.

First burdened with the responsibility to identify UFOs, the Air Force — in finding no proof for the extraterrestrial hypothesis — tacitly assumed in its inquiries that UFOs did not constitute an anomalous phenomenon. This assumption, according to Jacobs, called for the Air Force's systematic discrediting of UFO witnesses in order to prevent public hysteria about the UFO phenomenon, which resulted in criticisms from civilian UFO organizations and demands for the open scientific study of the UFO phenomenon. However, according to Jacobs, virtually all scientists in the 1950s and 60s who were involved in the controversy implicitly catered to the notion that the UFO phenomenon was not anomalous; scientists during this period took the same approach as the Air Force previously had — they attempted to explain the origins of UFOs without first establishing whether or not they represented a unique phenomenon. Presenting a similar argument to Ronald Story, Jacobs claims that scientists used nonscientific reasoning and "logical fallacies" to attack with prejudice the extraterrestrial hypothesis in order to establish UFOs within the confines of conventional phenomena.

Civilian UFO groups, according to Jacobs, also failed to establish whether or not UFOs constituted an anomalous phenomenon. The leaders of these groups, notably Donald Keyhoe — head of NICAP — often presumed that the UFO phenomenon was already established as anomalous and therefore represented extraterrestrial craft. As doubt about the Air Force's capability to deal with the UFO concern among the general public and scientific community mounted, the Air Force ceded scientific authority on the UFO phenomenon to the Condon committee, who the author argues "fell into the same trap as the others" by concerning itself first and foremost with the extraterrestrial hypothesis and not whether or not the phenomenon was anomalous in nature. Jacobs claims that in failing to find evidence confirming the extraterrestrial hypothesis of UFOs, the Condon group made the "common mistake" of concluding that the UFO phenomenon was not anomalous and therefore did not call for further scientific study.

Jacobs's main conclusion concerns a frequently occurring theme within his analysis: The failure of the main actors — the Air Force, the scientific establishment, and civilian UFO groups — "to ask the one question that offered some possibility of empirical resolution" to the UFO question. That is, the question of whether or not UFOs constituted an anomalous phenomenon. For Jacobs, the difficulty with which the UFO phenomenon presented itself to be analyzed within established scientific disciplines created a context in which this was the only "remotely answerable" empirical question. Although questions pertaining to the origin of UFOs "were at best highly theoretical and speculative," Jacobs points out that these were consistently the questions both UFO proponents and debunkers chose to answer. The author contends that by doing so, these actors perpetuated the UFO controversy and the confusion surrounding it.

However, the author lacks an adequate explanation as to why the question of whether UFOs constituted an anomalous phenomenon was the only "remotely answerable one." It occurs to me that given the "anecdotal and ephemeral nature" of UFO data, this question is in many ways no more easily answered — in an epistemological sense — than questions of the origin of UFOs. That is to say, scientists cannot distinguish in any absolute sense between fact and conjecture given "anecdotal and ephemeral" data. In general, Jacobs's argument would have benefited from a broader discussion of epistemology and scientific methodology.

There is at least one question that I would have liked to see answered by the author given the nature of his analysis. On what established scientific basis — given the above-mentioned nature of UFO data — can we say that UFOs constitute an anomalous phenomenon? Put another way, how can established scientific methodology distinguish between what is truly anomalous — unique phenomena that are not yet understood — and what may be understandable in terms of conventional science given more scientifically reliable data? I think that a greater discussion of the utility of scientific methodology in dealing with the UFO phenomenon would have immensely strengthened Jacobs's arguments.

Philip J. Klass in UFOs Explained (1974) takes a more skeptical stance towards the anomalousness of UFO phenomena than Story or Jacobs. His approach suggests that the methods of modern public-opinion pollsters — using a small, representative population sample to obtain an accurate description of the whole — can be applied to the UFO phenomenon. Klass argues in his historical analysis to "demonstrate that we now have more than enough cases and data to understand and explain the UFO mystery — providing these cases are analyzed objectively and scientifically, and providing the principles derived from such analyses are intelligently applied to similar cases." Klass aims then to draw generalities among UFO cases to establish the notion that the UFO phenomenon can be explained prosaically, virtually without exception.

Klass analyzes dozens of individual UFO cases — first through establishing patterns among similar cases such as "craft with illuminated windows," "high-flying UFOs," and "'extraterrestrial' UFOs" — and then by describing various cases of supposed "contactees," and abduction experiences and the effects of the media on the UFO phenomenon. The author also closely analyzes several individual cases — some of which have been pronounced unexplainable by prominent scientists such as J. Allen Hynek and historians such as Ronald D. Story. For example, regarding the 1973 "Army Helicopter Incident" in which an airborne helicopter encountered "a gray, metallic-looking, cigar-shaped object, with unusual lights and performing unusual maneuvers," Klass attempts to piece together several unrelated conventional events — for example, by assuming that the event's duration was far shorter than witnesses had claimed — to argue that the helicopter crew had misinterpreted Orionid meteors for a UFO. Seven years after the publication of UFOs Explained, Ronald D. Story still considers the Army Helicopter Incident to be "truly spectacular and unexplainable," suggesting that Klass's assumption that the experience took just a fraction of the time claimed by crew members may have been inappropriate. It is difficult to believe — as Klass claims — that the four military-trained crewmen were all incapable of distinguishing between "twenty seconds" and "four or five minutes."

Klass, however, views the unreliability of witnesses to be a cornerstone of what he terms "UFOlogical Principles" — principles that, upon a thorough analysis of the UFO phenomenon, are applicable to all UFO reports and which "in understanding the UFO mystery cannot be overemphasized." The author maintains several generalizations about the UFO phenomenon that attempt to relegate it to prosaic occurrences. For example, Klass contends that the inability of investigators to fully explain UFO reports does not support the extraterrestrial hypothesis. Despite this logic, however, the author deems unexplained UFO cases to be definitively terrestrial on the basis that future similar cases will shed light on their prosaic nature:

"The Rogers UFO case may remain unexplained for some years...but one thing is certain: if the object was only a few hundred feet away, and disintegrated in a blinding flash without leaving behind any residue on the ground, it certainly was not an alien spaceship."

Further, Klass argues that many UFO cases are deemed unexplainable simply because they have not faced rigorous investigation — and understandably so, on the basis that most UFO investigators cater to the extraterrestrial hypothesis. Each and every case presented — after being analyzed through various reports and investigated relative to potentially related conventional phenomena — is explained by Klass in prosaic terms.

Klass concludes that physical scientists — those most involved with the subject as UFO investigators — are handicapped in training and experience regarding the psychological component of the UFO phenomenon. With more support from skeptical-minded experts such as trial lawyers, criminal investigators, investigative journalists, and experimental psychologists — those trained to be "intrinsically wary of accepting statements as fact without deep probing and perhaps some 'discounting'" — scientists could more readily confront the complexity of the UFO phenomenon, which for Klass, involves a combination of physical science and human psychology. The most basic problem for the author, however, is that scientists attracted to the field of UFO investigation are inclined to believe in the extraterrestrial hypothesis. Like Ronald D. Story then, Klass contends that the difficulty with which modern science has had in dealing with the UFO phenomenon stems partly from the prejudices of contemporary scientists. Unlike Story, however, Klass claims that scientists drawn to the field of UFO investigation are biased in favor of the extraterrestrial hypothesis and therefore that the magnitude of the UFO controversy is due to this tendency. The cases analyzed, taken as a representative sample of the whole of UFO cases — for Klass — point to conventional explanations for all known reports.

I take issue with some of Klass's historical methods. Clearly, the author is forced by the "anecdotal and ephemeral nature" of UFO data — to use David Michael Jacobs's terminology — to make a priori assumptions about the conventional phenomena he implicates in all known UFO cases, as indicated by the example of the "Army Helicopter Incident" given earlier. Is it logical then for Klass to debunk individual cases on foundations of a priori assumptions, while simultaneously refusing to accept arguments from UFO proponents — for example, that UFOs constitute an anomalous phenomenon — on the basis that they are not justified a posteriori? In other words, is it fair for Klass to assume independent of empirical evidence that all UFO reports are conventionally explainable — if not presently, then at a time when future similar reports can exemplify their prosaic nature?

It seems to me that in an epistemological sense, some of Klass's explanations are based on conjecture — arguably no less so than explanations of UFOs as extraterrestrial crafts. As I think Ronald D. Story rightfully points out, contemporary science is in many ways limited in its capability to provide definitive knowledge — at least in the matter of explaining UFO phenomena. Established scientific methods call for empirical, reproducible, observable, and measurable results — criteria that the data pertaining to the UFO phenomenon surely cannot provide at the present time. Therefore, it may be inaccurate to assume — as Klass does — that contemporary science alone can enable us to fully "understand and explain the UFO mystery."

Furthermore, Klass's approach of using a small, representative sample to generalize about all UFO phenomena — on the basis of the success of modern pollsters in employing such methods — may not be applicable here. It is clear to me from researching hundreds of well documented descriptions of UFO cases that the phenomenon is not homogeneous — it cannot be explained away with vast generalizations that do not address the distinctive nature of individual cases. Arguments that attempt to make such generalizations about all UFO phenomena — especially while implicating conventional events solely on the basis of a priori assumptions that disagree with witness statements — are inevitably doomed to the domain of conjecture. While Klass presents an impressive historical account of UFO cases and potential prosaic explanations for such cases, his goal of definitively explaining the UFO phenomenon has not been fulfilled. The limits of contemporary science and — perhaps equally important — the widely divergent and heterogeneous nature of UFO cases suggests that historical methods which operate on such vast generalizations cannot be applied to the UFO phenomenon to any definitive ends.

I am not quick to agree with claims that contemporary science either can solve the question of the anomalousness of the UFO phenomenon — as David Michael Jacobs claims — nor has solved that question — as Philip J. Klass contends. As both Ronald D. Story and David Michael Jacobs note, the methods of established scientific disciplines are largely incapable of analyzing the data pertaining to UFO cases. Until compelling new evidence or new investigative methods are established, contemporary science will remain incapable of solving most questions surrounding the UFO mystery. I agree with Ronald D. Story in that the limitations of science to deal with the UFO phenomenon indicates that the pertinent discourse is greatly in need of a focus on the philosophy of science — notably regarding epistemology.

If scientists and historians of science were to view the phenomenon and its pertaining data within an epistemologically focused scope, perhaps both UFO proponents and skeptics — and everyone in between — could reach a consensus regarding the conspicuously limited state of our current knowledge on the subject. J. Allen Hynek, the prominent astronomer and Air Force consultant on UFOs, wrote in 1966:

"There is a tendency in 20th-century science to forget that there will be a 21st-century science, and indeed, a 30th-century science, from which vantage points our knowledge of the universe may appear quite different. We suffer, perhaps, from temporal provincialism, a form of arrogance that has always irritated posterity."

It is perhaps with this consideration in mind that scientists and historians of science will be best prepared to approach the arduous and potentially endless task of separating fact from conjecture within the great UFO mystery.