A logical definition insists upon a proximate genus and differentia. But as there is no genus higher than the highest genus (summum genus) then surely such cannot be defined logically. The words being and thing illustrate terms of this class. Moreover, it is impossible to give a satisfactory definition of an individual (infima species) as no attributes can be mentioned which will distinguish definitely and permanently the individual from others of the class. We may perceive the attributes but not those that are possessed solely by the individual. To say that Abraham Lincoln was a man who was simpleand honest is not a definition, as other men have had the same characteristics.
Again there are a few terms such as life, death, time and space which cannot be defined satisfactorily. These terms seem to be in a class by themselves or of their own genus (sui generis).
Since a definition of a term is a brief explanation of it by means of its attributes, it follows that collective terms and terms standing for a single attribute are incapable of definition. Such terms as group, pain, attribute, belong to this class.
We may say, then, that there are some terms too high, some too low and some too peculiar to come within the province of logical definition. In short, “summum genus,” “infima species” and “sui generis” are incapable of definition.
9. DEFINITIONS OF COMMON EDUCATIONAL TERMS.
(1) Development is the process whereby the latent possibilities of an individual are unfolded or the invisible conditions of a situation are made apparent.
Development means expansion according to principle, while unfolding may or may not involve a principle.
(2) Education is the process employed in developing systematically, symmetrically and progressively all of the capabilities of a single life; or
(3) Education is the process of modifying experience in order to make the life as valuable as it ought to be.
(4) Teaching is the art of occasioning those activities which result in knowledge, power and skill.