ABSTRACT
Although now rendered in a relatively simple form, which makes its principles understandable to elementary school children, measurement is sophisticated, the practice of which has led to the remarkable advancement of the natural sciences. Measurement is concerned with properties considered in terms of more or less, and measured by instruments that operate in some relevant range. A scientific theory is seen consistently to summarize a coherent body of knowledge that purports to not only describe but also to explain a class of related substantive phenomena. Measurement is distinguished by a unit. The idea of a unit can be illustrated readily with the idea of a beam balance for measuring mass. The structure among measurements in any scientific theory is extremely simple. A measurement theory needs to be compatible with known features of measurement. The nature of the engagement between objects and agents in the frame of reference is part of the empirical design.
