Full Idea
We can say in advance that we use the term 'tiger' to designate a species, and that anything not of this species, even though it looks like a tiger, is not in fact a tiger.
Gist of Idea
'Tiger' designates a species, and merely looking like the species is not enough
Source
Saul A. Kripke (Naming and Necessity lectures [1970], Lecture 3)
Book Reference
Kripke,Saul: 'Naming and Necessity' [Blackwell 1980], p.121
A Reaction
This is the 'baptismal' direct reference theory applied to species as well as to particular names. It seem to hinge on an internal structure being baptised, despite ignorance of what that structure is. Cf nominal essence? 'Tiger' denotes their essence?