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Intelligence analysis involves turning raw data into applied information through a process of process, interpretation and analysis. These elements are used in intelligence analysis, scientific reasoning and in our daily lives. John Stuart Mill was a philosopher who studied the field of logic. He wrote a series of canons, or methods for logically determining the cause of events.
Mill’s First Canon
“If two or more instances of the phenomenon under investigation have only one circumstance in common, the circumstance in which alone all the instances agree, is the cause (or effect) of the given phenomenon.”
If after eating fish at a restaurant, two individuals both get sick – we may conclude that the fish is the cause of their illness if they have nothing else in common and nobody else got sick.
Mill’s Second Canon
“If an instance in which the phenomenon under investigation occurs, and an instance in which it does not occur, have every circumstance save one in common, that one occurring only in the former; the circumstance in which alone the two instances differ, is the effect, or cause, or a necessary part of the cause, of the phenomenon.”
If the two individuals who eat fish get sick, but one was prepared by a known chef and the other is prepared by a new cook, it’s likely something done by the new cook was related to the contamination.
Mill’s Third Canon
“If two or more instances in which the phenomenon occurs have only one circumstance in common, while two or more instances in which it does not occur have nothing in common save the absence of that circumstance; the circumstance in which alone the two sets of instances differ, is the effect, or cause, or a necessary part of the cause, of the phenomenon.”
If while playing paintball and your enemies appear to be able to hit you very well when using a new scope, but return to average levels of aim when the scope is removed, you can assume the increased accuracy is because of the scope.
Mill’s Forth Canon
“Subduct from any phenomenon such part as is known by previous inductions to be the effect of certain antecedents, and the residue of the phenomenon is the effect of the remaining antecedents.”
This is essentially the process of elimination. Removing any parts (e.g. of a machine) where you know what their function is. This leave only the parts whose functions you don’t know. When you know what should occur, you can assume the remaining occurrences are due to the parts you haven’t assigned yet.
Mill’s Fifth Canon
“Whatever phenomenon varies in any manner whenever another phenomenon varies in some particular manner, is either a cause or an effect of that phenomenon, or is connected with it through some fact of causation.”
When two different fish recipes have the same taste of bitterness and the only thing they have in common is the presence of anchovies, you may begin to assume the anchovies are the cause of the bitterness.
Clauser, J. (2008) An Introduction to Intelligence Research and Analysis. Goldman, J. (Ed.). Lanham, MD: Scarecrow Press