OSTENSIVE DEFINITION

When asked what you mean by a word, a natural response might be to point out an instance of the thing you have in mind. For instance, if you were taking a botany course and asked "What is a conifer?," the instructor might take you to the window and point to a fir tree saying "That is a conifer" then pointing to a row of different trees say "those are deciduous." From this you would have some better understanding of the use of the terms. These would be ostensive definitions (ostensive, from the latin ostendere, meaning to show). Note that the examples I just gave do the work of ostensive definition. Rather than describe what such a definition is, I pointed out instances.

The power of such definition is in directly presenting a concrete and complex instance of what you mean. Yet, in presenting individual instances of a larger class we leave open many ambiguities. In the above case, a student might conclude that all conifers are fir trees. It may be clearer to inform a student that a conifer is a tree or shrub that keeps it foliage year round and bears cones. This goes far beyond ostensive definition by distinguishing a class of things to which the individual thing belongs.

Another weakness of ostensive definition is in dealing with very complex or abstract ideas. Clarifying what we mean by freedom, love, truth and other concepts that philosophy frequently deals with will be difficult by ostention. Granted, getting clear on these concepts will be difficult by any method, still it seems clear that ostensive definition alone will not suffice.