A notable aspect of the problem-solving process--the primary task of the literary detective--is the continuous interplay between existing knowledge and knowledge directly related to the case in hand. This article focuses on describing and comparing the investigative approaches of arguably the three most famous literary detectives of the first half of the twentieth century, created respectively by Arthur Conan Doyle, Agatha Christie, and Georges Simenon, namely, Sherlock Holmes, Hercule Poirot, and Inspector Maigret, with reference to three bodies of knowledge: a body of knowledge existing prior to the investigation, knowledge of the investigative methodology to be used, and case-specific knowledge, gained in the course of the investigation.
Knowledge that the investigator has prior to the investigation includes specialized factual knowledge and/or knowledge gained through previous experience. By drawing on a reservoir of specialized technical knowledge, the investigator is able to identify and interpret concrete data of which the meaning and significance escape his rivals. At the same time, or alternatively, the investigator has a mental catalogue, derived from previous investigations, containing information on crimes, criminal types, patterns of behavior and so on.
Confronted with a set of events for which he has to find a rational explanation, the detective could use this body of knowledge as basis for a kind of encyclopedia, in which phenomena are grouped, annotated, and contextualized, and for a "dictionary" which enables him to interpret certain gestures and other observable phenomena; (1) or, through analogical thinking, to anticipate or interpret certain actions or events; to typify a suspect or clarify the profile of the victim; or to open up a line of investigation based on a technical understanding of particular data. In this respect, the investigator resembles a scientist who, upon observing a set of unexplained phenomena, first of all tries to explain it in terms of knowledge already at his disposal. The scientist works from the observed phenomena to its possible causes. If he succeeds in finding a readily available explanation that adequately accounts for these phenomena, further investigation becomes superfluous. Only if such an explanation cannot be found, or if a readily available explanation is found inadequate, do the phenomena become a problem worthy of further investigation. The search for a solution to the problem is continued by advancing conjectures that the investigator attempts to refute in view of the available data, until a solution is found that can stand up to critical scrutiny. In the process of looking for a satisfactory explanation, the investigator makes use both of a first body of knowledge concerning phenomena similar to those constituting the problem (2) and a second body of knowledge related to the methodology accepted in the discipline concerned. (3)
The detective usually cannot simply apply existing explanations to the case in hand in order to arrive at a solution, inasmuch as each case presents a new problem, involving different persons and events. Yet, knowledge gained from previous cases could facilitate the identification of clues and assist the detective in finding the correct lines of investigation, especially where problems are generically related. The nature of the problem remains basically constant, in that it always involves identifying the perpetrator of a crime, so that the investigative method of a particular detective does not change significantly from case to case.
The scientific process is largely conventionalized; it starts with the unambiguous formulation of a problem that can be solved with the "available methods of scientific inquiry," moves through the formulation and testing of one or more possible solutions, and culminates in the presentation of a solution that can be confirmed at least provisionally. (4) Similarly, the methodology to be used by the detective usually follows a basic pattern: once the basic facts of the problem are known, the detective systematically interviews and interrogates those involved, searches for and follows leads, regularly reviews the case up to that point, and puts forward hypotheses for the solution. …