In 1959, Calvin Mooers, one of the pioneers of Information Retrieval, set forth what he called a "contradictory principle" of the fledgling science, and attached his own name to it:

Since that time, his law has been widely referenced, especially in recent years as Information Retrieval has become more central to our society and our individual lives; a by-no-means exhaustive survey of the World Wide Web and the literature of various disciplines (Business, Education, Computer Science, and Library Science) reveals several dozen citations from the last decade alone. An interesting thing has happened to Mooers’ Law, however, along the way to acceptance: the law that is becoming widely held as true by information professionals is not the same one that Mr. Mooers proposed.

The difference between the actual law and its mutation centers specifically upon a misinterpretation of the word "have", a misinterpretation which perhaps results primarily from reading the law excerpted from the original article in which it appeared, and applying it to a concern that is distinctly separate from the one Mr. Mooers was attempting to address. What follows, then, is an effort to compare and contrast what are really two very different Mooers’ Laws, which for the purposes of this discussion will be categorized as "In" and "Out of" context.

The Law In Context

Mr. Mooers originally proposed his law during a panel discussion at the annual meeting of the American Documentation Institute at Lehigh University in October, 1959; the remarks he made there were "excerpted, with modifications" from his Information Retrieval Selection Study, Part II: Seven System Models, written earlier that same year. The law then appeared in print as a brief paper in Zator Technical Bulletin 136 in December, and as an editorial the next year in American Documentation (1960). More recently, it has been reprinted in The Scientist, both in paper format and on-line (1997).

Mooers’ Law, as he explains it, focuses on the "painful and troublesome" aspects of having information in hand and therefore feeling obligated to do something with it; in his estimation, given what he calls the "present intellectual and engineering climate" (1959b, p.1), the customer might just as well wish not to have the information, even if it is readily available. For, he notes, "If you have information, you first must read it, which is not always easy. You must then try to understand it. To do this, you may have to think about it"(1959b, p.2).

In Mr. Mooers’ own words, what he is setting forth is a "principle . . . of behavior" (1959b, p.1), and his concern is with changing a climate in which that behavior is more often rewarded than punished. The ability of an information retrieval system to quickly and efficiently place information in the customer’s hands is not the issue; indeed, that is what Mr. Mooers is lamenting.

In his original Seven System Models study, he goes even further, setting forth the following as a corollary to his as-yet-unnamed principle: "Where an information retrieval system tends not to be used, a more capable information retrieval system may tend to be used even less" (1959a, p.34).

This is not only different from the Mooers’ Law that appears so frequently in the literature of today, but given a particular "intellectual . . . climate" such as the one he describes, distinctly at odds with it.

The Law Out Of Context

Mooers’ Law, as it is now popularly perceived among what might be termed the "Information Community", focuses upon the effort that the user of a retrieval system must put forth in order to acquire the desired information. J. Michael Pemberton, ostensibly quoting Mooers, has restated this succinctly as follows: "The more difficult and time consuming it is for a customer to use an information system, the less likely it is that he will use that information system" (1989, p.46 ). Roger K. Summit, Chairman Emeritus of DIALOG Information Services, phrases it another way: "Mooers’ law tells us that information will be used in direct proportion to how easy it is to obtain" (1993, p.16).

This interpretation of the law is generally used as a cautionary tale to those who would provide access to information: If you build it, and make it too hard, they will not come. To anyone who has used a difficult search engine or database interface, this has the ring of truth to it, and that may be why Mooers’ Law, once removed from its original context, has resonated on the Internet and within the literature of Information Science; here, it seems, is the original articulation of many of our current frustrations. While those frustrations may indeed be valid, they are not the same ones that led Mr. Mooers to compose his "contradictory principle": the Information Community of today (and yesterday as well, according to Mooers) assumes that users want information and would acquire it if it were easy enough to obtain; he reflects that, sadly, this may not always be the case (1959a, p.1).

Both concerns--that customers will not use IR systems because having the information is too much trouble and because getting the information is too much trouble--are ultimately behavioral in nature, and both adhere to what Esther G. Bierbaum sets forth as a "unifying principle" for library and information science (1990, p.18), namely Zipf’s "Principle of Least Effort", which contends "that the entire behavior of an individual is at all times motivated by the urge to minimize effort" (1949, p.3), but they are clearly separate problems, with separate solutions. We, that is the Information Community of today, assume that there is a technical solution to our concern: if we can build systems that are faster, more intuitive, and provide the customer with results that more nearly match what he or she requested, then those systems will be heavily used. Mooers suggests that the solution to his concern lies in changing the culture that created it, and acknowledges that this is "no easy task" (1959a, p.39). Again, it is important to emphasize that this solution lies outside the realm of hardware and software; in the conclusion of his Seven System Models study, Mooers clearly states that, in a culture such as the one he describes, "the amount of use of a retrieval system depends upon the intellectual environment or social climate surrounding the system, and not upon the faults or merits of the system itself" (1959a, p.39).

The Context of Environment

Mooers acknowledges that his law, if true, is a "pessimistic . . . even a cynical conclusion" (1959a, p.32; 1959b, p.1), and at first glance such a conclusion would seem to paint his entire career, and those of others in the field, as a futile endeavor, but for the fact that the law is restricted to certain "user environments" (1959a, p.2). This turns out to be an important point. The specific environment that Mooers was addressing was one that he believed existed within "many companies, laboratories, and agencies" of his day, an environment in which "rewards, instead of punishment, go with not using information" (1959b, p.1-2). He acknowledges, however, that "there are situations where the diligent finding and use of information is stressed and rewarded, and where failure to find or to use information is severely punished" and notes that "in such places, we can expect retrieval systems will be actively used" (1959b, p.2). In his Seven System Models study, he cites "the best of the chemical or pharmaceutical laboratories" as examples of this type of environment, ones in which "management . . . is well aware of the dollar costs and legal hazards of not making use of information" (1959a, p.33). Earlier in the same study he points out that, in an environment such as this, "where the need [for information] is high enough" even "fundamentally poor systems may be well used" (p.5).

Based on these observations, then, what might be termed a Scale of Information Retrieval Environments suggests itself. On one end of the scale there are environments in which it is far more painful to have information than to not have it; on the other end the exact opposite is true. What is interesting about these extremes of the scale is that in either case, at least theoretically, the performance of the IR system will not affect the amount of its use since in the one no improvements in design or efficiency will entice the user to acquire information that will cause him such inconvenience, while in the other no amount of frustration inherent in using the system will deter him from discovering information that he knows is absolutely vital to (for example) his continued employment. Surely, though, most environments that include information retrieval are not at either end of the scale but rather somewhere in between, and it seems logical to suggest that, within this "in between", system performance does matter. Indeed, it might be argued that, as one approaches the midpoint of the scale, performance becomes the critical factor in whether or not the system is used.

If one accepts this "Scale of Information Retrieval Environments", then perhaps it can finally be seen how the Mooers’ Law that is "in context" can coexist with that which is not: the first would hold true in environments at one extreme of the scale, while the second would hold true at, or near the midpoint. It follows, as well, that if we were to combine these two laws with yet a third, one addressing the other extreme of the scale, then it might be possible to articulate a set of principles that would govern the use of systems in any such type of IR environment.

Mooers’ Law Expanded

It seems unlikely that Mooers, in spite of the attention he focuses upon environments in which IR systems tend not to be used, was unaware of the rest of the scale; his observations about "the best of the chemical or pharmaceutical laboratories" acknowledge the opposite extreme, while the very study in which his law is first mentioned seems to exist primarily to address the needs of those environments that are in between. Indeed, early on in this Seven Model Systems study, he makes a statement that very closely resembles what his law has now become: "If the burden on the users of the information becomes too high, either in the retrieval process or in the labor of delineating new material, the users will give the system up and try to get along without it" (1959a, p.6). Clearly, though, this statement has no meaning within either of the environments which lie at the extreme ends of the scale; it makes sense only if applied to the middle. Thus, it would seem that an expansion of Mooers’ original law would be in order:

Mooers’ 1st Law: In an environment in which it is more painful and troublesome for a customer to have information in hand than for him not to have it, an IR system will tend not to be used.

Mooers’ 2nd Law: In an environment in which it is absolutely critical for a customer to have information, an IR system, no matter how poorly designed, will tend to be used.

Mooers’ 3rd Law: In an environment in which the trouble of having information versus that of not having it are fairly evenly balanced, system design and performance tend to be the deciding factors in whether or not an IR system will be used.

Bierbaum, E.G. (1990). A paradigm for the ‘90s: in research and practice, library and information science needs a unifying principle; "least effort" is one scholar’s suggestion. American Libraries, 21, 18-19.

Mooers. C.N. (1959a). Information Retrieval Selection Study. Part II: Seven System Models. Cambridge, MA: Zator Company.

Mooers, C.N. (1959b). Mooers’ Law; or why some retrieval systems are used and others are not. (Zator Technical Bulletin 136). Cambridge, MA: Zator Company; 1959. Editorial of same title, American Documentation, v.11, no.3, page i; July 1960; and reprinted in The Scientist, v.11, no.2, p 10 Mar 17, 1997.

Pemberton, J. Michael (1989). Telecommunication: Technology and Devices. Records Management Quarterly, 23, 46-48.

Summit, Roger K. (1993). The Year 2000: dreams and nightmares. Searcher, 1, 16-17.