Learn Turkish: Asıl gaye, herkes tarafından duyulmaktır. - The main purpose is to be heard by everyone.

This highlights the main point of this lesson! Adding the copula -tır (which acts like "is") to the infinitive -mak turns the action into the sentence's main predicate. It gives us "is to be heard". You can drop it and just say duyulmak, but -tır makes the statement sound more definitive and complete.

What is the exact breakdown of the word duyulmaktır?

It starts with the verb root duy- (to hear). Next is the passive suffix -ul-, making it duyul- (to be heard). Then we add the infinitive marker -mak to turn it into a noun-like concept, and finally the copula -tır to make it the predicate.

How does tarafından function in this context?

The word tarafından translates to "by" when used with passive verbs. Because duyulmaktır is passive, herkes tarafından specifies the agent performing the action, meaning "by everyone".

Are gaye and amaç completely interchangeable?

Yes, both mean "purpose" or "goal". Gaye is an older loanword from Arabic, whereas amaç is of Turkic origin. You can use either, though asıl amaç is slightly more common in modern daily speech.