One of the complications of the drafting principle to be ‘accurate’ is a drafter’s tendency to be exhaustive or to ascertain that the concept is well-covered. An important guideline for improving your accuracy (and accordingly your confidence that you did a good job) is to think analytically and draft conceptually, in McKinsey’s terminology, ‘MECE’ (mutually exclusive, collectively exhaustive) or, in French philosophical terms, ‘cartesianic’.
MECE and cartesianic mean that, consistent with the ideas of Descartes, the drafter cuts the greater contractual concepts into understandable pieces in respect of which he or she is convinced that those pieces are all the pieces, because they leave no gaps and do not overlap.
McKinsey’s principle to be ‘MECE’. The two related concepts of ‘mutually exclusive, collectively exhaustive’ can be explained as follows: a description of acts or events is ‘collectively exhaustive‘ if no other act or event is conceivable. In contract drafting terms it means that describing a course of action is collectively exhaustive if all variants are caught (under the addressed conditions or circumstances). When you roll a dice, it will inevitable show a 1, 2, 3, 4, 5 or 6 and they capture all possible outcomes exhaustively. ‘Mutually exclusive‘ are subject matters that exclude each other without any overlap. If you throw a coin, you can rest assured that the outcome is either heads or tails (yes, if you throw it in on the beach it might show the edge, which is why arguably the edge makes heads and tails collectively exhaustive, but still is mutually exclusive).
Descartes. The MECE-principle was probably identified by the 17th century philosopher and mathematician René Descartes. In his Discours de la méthode, and more elaborately in his Regulae ad directionem ingenii (i.e., rules on the direction of the mind), he restated a few principles to deduct, on the basis of a hypothesis, an explanation or description of any investigated problem. Traditionally, the French PhD-doctorate books are set up according to Descartes’ method. Descartes proposed that:
“if we are to understand a problem perfectly, we must free it from any superfluous conceptions, reduce it to the simplest terms, and by a process of enumeration, split it up into the smallest possible parts.”
Drafting technique. Now, let’s translate this into contract drafting. A draftsperson often deals with the question how to address a subject of discussion (or agreement) in such manner that the future will not show lacunas or reveal an interpretation that had not been put into the words by the parties. The task of a drafter is therefore to think analytically, to create a systematic structure, and to write logically. To identify the smallest possible parts, the drafter may revert to concepts such as:
substance vs. procedure
objective elements vs. subjective elements
content vs. form
cause vs. effects
a concept vs. manifestations of the concept
(chrono-) logical sequence: before and after delivery/closing
 The MECE-principle (pronounce MEESEE, like in see me) is addressed in two bestsellers of Ethan Rasiel (McKinsey). Ethan M. Rasiel, The McKinsey way, McGraw-Hill 1999; and Ethan M. Rasiel and Paul N. Friga, The McKinsey mind, McGraw-Hill 2002 (both are translated into several languages).