Three problems with this theory: 1) We normally know only a few members of the reference class, yet we understand the meaning of the word. I haven’t seen all the dogs in the world (happily), but I know the meaning of the word. 2) Some words have no reference class, yet are meaningful, e.g., prepositions and conjunctions: have you ever seen an “if” or stumbled on an “after”? Even adjectives and verbs, like “blue” or “look,” cannot be observed, only blue things or someone looking. And what about “Santa Claus” (sorry to destroy the myth), “unicorn,” or “the first man to land on Mars”? 3) Some meaningful phrases have a reference we may not know, e.g., “the oldest man in the world.” .

1. Three problems with this theory:
1) We normally know only a few members of the reference
class, yet we understand the meaning of the word. I haven’t
seen all the dogs in the world (happily), but I know the meaning
of the word.
2) Some words have no reference class, yet are meaningful, e.g.,
prepositions and conjunctions: have you ever seen an “if” or
stumbled on an “after”? Even adjectives and verbs, like “blue”
or “look,” cannot be observed, only blue things or someone
looking. And what about “Santa Claus” (sorry to destroy the
myth), “unicorn,” or “the first man to land on Mars”?
3) Some meaningful phrases have a reference we may not know,
e.g., “the oldest man in the world.”