The difference between nouns preceded by the article “a” and by “the”

[Joe Carillo]

Question by Prashant Solanki in New Delhi, India, on the Forum’s Facebook Gateway (August 14, 2017):

Which is correct, sir?

“____ bicycle is an environmentally friendly means of transportation.”

(1) A
(2) The

Can you explain it, please? If both, then what is the difference between in their meaning?

My reply to Prashant:

Here’s the difference: When the indefinite article “a” is used, as in the sentence “A bicycle is an environmentally friendly means of transportation,” the reference is to any particular bicycle among all kinds of bicycles. In contrast, when the definite article “the” is used, the reference is to the bicycle as a generic form of two-wheeled transport driven by foot pedaling. It can be validly argued though that the first sentence, “A bicycle is an environmentally friendly means of transportation,” is a semantically flawed sentence because it actually defines “bicycle” as a generic term, which means that the definite article “the” should be used instead for such usage. The use of the indefinite article “a” will be perfectly defensible only in such sentences as “A bicycle was left behind under the mango tree” or “No one wants a bicycle with a very bumpy ride,” both of which refer to a particular bicycle and not to the generic term.

  THE BICYCLE AS A FORM OF FOOT-PEDALED TRANSPORT             A BICYCLE DRIVEN BY A WOMAN

I would like to invite you to visit Jose Carillo’s English Forum for answers to many such English grammar questions. A good way to begin is to check out the Forum’s Playlist Update for July 22 - 28, 2017 for its Gateway on Facebook. Everything should follow very nicely from there.