I saw throughout a technical document the use of the conjunction “if” where the conjunction “whether” was required.

Problem:
The conjunction “if” is not a synonym for the conjunction “whether” in formal writing.

Explanation:
A technical document should contain formal writing. I recently reviewed a technical document that contained such sentences as “Call the LDAP Screening class to determine if the LDAP server is affected.” This exemplifies incorrect use of the conjunction “if”; correct use is exemplified by a sentence such as “If an association is not found, remove that association from the list to be deleted.”

The “Call the LDAP Screening …” sentence should be rewritten as “Call the LDAP Screening class to determine whether the LDAP server is affected.”

The problem with using “if” to introduce a clause indicating uncertainty is that the use of “if” can sometimes create ambiguity (especially in writing).

For example, “Let him know if he has won the contest.” could mean:

• “Let him know, if he has won the contest.” (Don’t let him know, if he has not won the contest.)
  -OR-
• “Let him know whether he has won the contest.” (No matter how the contest ends, let him know.)

I believe that the use of “if” as a substitute for “whether” — even in formal writing — supports my “Devolution toward Simpler” hypothesis. It’s much simpler to say or write “if” than to say or write “whether”. The one-syllable conjunction “if” can be spoken quickly. The two-syllable conjunction “whether” demands that its first syllable be held longer than average so that the listener doesn’t confuse the word with the noun “weather” upon first hearing it (without the context of a complete sentence).

Solution:
Use “whether” to introduce a clause whose certainty is unknown. Use “if” to introduce a clause in the indicative that is presupposed to be consistent with fact. Use “if” to introduce a clause in the subjunctive that describes an occurrence that is presupposed to be contrary to fact.