Overview
"If names be not correct, language is not in accordance with the truth of things." Thesaurus of Educology (2026) opens with these words of Confucius and applies that ancient worry to education. Its premise is that the ordinary language used in discourse about education abounds with ambiguity, and that ambiguity is a source of confusion, mistaken inference and fruitless dispute. Its remedy is the patient disambiguation of terms and the provision of a shared, well-defined vocabulary — a thesaurus — for careful educological discourse.
Education and Educology
The book begins from the distinction that runs through all of Christensen's work. Education is the field of phenomena in which someone takes on the role of teacher and teaches, and someone takes on the role of student and studies intentionally under guidance, some content in some setting, so that the student learns intentionally under guidance some prescribed range of knowing as specified by some intended learning outcome. Educology is the fund of knowledge about that field — the set of recorded true statements produced by successful, careful, well-disciplined educological inquiry. Christensen distinguishes the recorded contents of educology as facts, descriptive theory, explanatory theory, praxiological theory and normative theory, and he distinguishes the users of educology, the teachers of educology and the educologists (the researchers) who produce it.
The Problem of Ambiguity
The heart of the book's motivation is that a single term in discourse about education is routinely made to carry several different meanings. The term education alone is used to denote a teacher, learning as a process, a range of knowing, the activities of teaching and intentional guided studying, and the recorded true statements about all of these. Learning denotes both the process of coming to know and the cognitive state that results from it. Knowledge denotes both recorded true statements and a state of mind. Educator denotes a teacher of any content at any level and a teacher of educology. When terms slide among meanings unmarked, careful reasoning becomes impossible.
Educological Descriptive Theory
Christensen's response is educological descriptive theory: a set of well-defined, explicated and exemplified terms with which the elements, relations, activities, processes and products of education can be characterized, discerned and described. Such terms are produced by educological inquiry that uses the rules of definition as its discipline and the techniques of conceptual analysis as its method. The book illustrates the method with a disambiguation test: a candidate definition (the definiens) is substituted for a term in an ordinary sentence, and the substitution succeeds when it leaves the sentence's meaning unchanged. By this method the several senses of a term are separated and marked — for example, the senses of education are distinguished as education₁ through education₅, and the senses of teaching as teaching₁, teaching₂ and teaching₃ — so that a reader always knows which is meant. On this analysis, education in the sense of teaching and intentional guided studying (education₄) is identified as the proper object of knowledge for educology, because it alone satisfies the criteria of inclusiveness, exclusiveness, internal consistency, exhaustiveness, external relatedness and fruitfulness.
Education as a System
A central achievement the book builds on is the systems conception of education first developed by the American educologists Elizabeth Steiner Maccia and George Maccia (1966). On this conception, education (E) is not a vague abstraction but a system, and it can be stated exactly. In set notation, E = T ∪ S ∪ C ∪ X: education is the union of its four essential elements — teacher (T), student (S), content (C) and context (X) — all standing in relation to one another. These four are essential in the strict sense that removing any one of them dissolves the system: without a teacher, or a student, or content, or a context, there is no education.
Each element is itself defined precisely and, where ordinary usage is ambiguous, resolved into parts. Content is didactically organized knowledge and/or a didactically organized range of knowing (C = C₁ ∨ C₂). Context is the union of a physical location, a social setting and a cultural milieu (X = XP ∪ XS ∪ XC). Within this system there are two basic activities — teaching and intentional guided studying — whose intended product, when they are effective, is the student's intentional guided learning of a prescribed range of knowing. Representing education in this way makes it possible to say exactly what belongs to the field of phenomena under study and how its parts are related.
A Notation for Educological Discourse: What Is, and Is Not, Education
Because the elements and the disambiguated senses of terms are each defined precisely, the relations among them can be expressed with the ordinary operators of set theory — union (∪), and inclusion or superset (⊃). This is where the notation earns its keep: it shows exactly what falls within education and what does not. A broader sense of a term is written as a superset of a narrower one. Teaching in its primary sense (teaching₁) — deliberately providing opportunities, guidance, advice, assistance and supervision to a student who studies intentionally under guidance — is a superset of effective teaching (teaching₂): teaching₁ ⊃ teaching₂, because teaching₂ is simply teaching₁ that has succeeded in producing learning. Teaching₁ is itself the union of its effective and ineffective instances: teaching₁ = (effective teaching₁) ∪ (ineffective teaching₁). The point the notation preserves is that teaching₁ is a task, not a guarantee — just as one can fish without catching anything and still have been fishing, one can teach₁ without the student learning and still have been teaching.
The same precision marks off what education is from what it is not. Education in the sense of teaching and intentional guided studying (education₄) is the encompassing system — the union of teacher, student, content and context, together with its two activities — and it is this sense that serves as the object of knowledge for educology. A range of knowing considered by itself (education₃), by contrast, is not that system at all: it is a product of education that excludes teachers, teaching, students and studying, and so is too exclusive to count as education. And the recorded true statements about education are not education either; they are educology (education₅) — knowledge about the field rather than the field itself. By fixing these relations in notation, the book makes claims about education explicit and checkable, so that they can be stated — and examined — without equivocation.
The Thesaurus
The book is organized in three parts. The first develops the account of educological discourse and descriptive theory sketched above. The second is a thesaurus of special symbols for use in educological discourse. The third is a thesaurus of well-defined terms for use in educological discourse. Together they are offered as a controlled vocabulary for the field — a shared set of terms and symbols that lets independent researchers, practitioners and policy makers combine their work without first having to re-negotiate what their words mean.
Why It Matters
A controlled vocabulary is not a scholarly indulgence. The coherence of curricula, the fairness of assessment and accountability regimes, and the soundness of education policy all depend on the clarity of the concepts they are built from. By insisting that names be made correct, Thesaurus of Educology aims to make serious, well-founded discourse about education possible — which is, in the end, the precondition for improving education itself.