Also called the natural state model of species, this was based on the ideas of Greek philosopher Aristotle (384-322 BC), and applied by Swedish botanist Carolus Linnaeus (1707-1778) and others in their search for the perfect ‘type specimen’ for each species.
It is the concept that all members of a species share a common natural state that serves to define and separate them from other species, with observed variations in individuals of a species being caused by forces that interfere with the organism’s attainment of its natural state.
This pre-evolution perspective holds that species are fixed entities, a view no longer accepted by biologists.
Also see: theory of speciation, theory of species
Compare with: POPULATION THINKING
Scientific essentialism, a view espoused by Saul Kripke and Hilary Putnam, maintains that there exist essential properties that objects possess (or instantiate) necessarily. In other words, having such and such essential properties is a necessary condition for membership in a given natural kind. For example, tigers are tigers in virtue of possessing a particular set of genetic properties, but identifying (or appearance-based) properties are nonessential properties. If a tiger lost a leg, or didn’t possess stripes, we would still call it a tiger. They are not necessary for being a member of the class of tigers.
It is important, however, that the set of essential properties of an object not be used to identify or be identified with that object because they are not necessary and sufficient, but only necessary. Having such and such a genetic code does not suffice for being a tiger. We wouldn’t call a piece of tiger tail a tiger, even though a piece of tiger tail contains the genetic information essential to being a tiger.
Other advocates of scientific essentialism include Brian Ellis, Caroline Lierse, John Bigelow, and Alexander Bird.