This represents a fairly common problem of syntax and morphology not lining up with each other.  Certainly "to eat" is an infinitive, but "to" also cliticizes to "going" when "going to" acts as a modal, as shown by its contraction to "gonna".  When "going" is used with its motion meaning, as in

Speaker A:  I'm going to Muncie to meet a friend for lunch tomorrow.
Speaker B:  I'm going to use the Ball State library.

Speaker B can't contract and still maintain the parallelism with Speaker A.

Another instance of morphology/syntax conflict is the contracted 's from "is" as in "The ball's in play."  Even though the predicate is clearly "is in play," the contracted copula cliticizes to the last word of the subject.

Herb

Herbert F. W. Stahlke, Ph.D.
Emeritus Professor of English
Ball State University
Muncie, IN  47306
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From: Assembly for the Teaching of English Grammar [[log in to unmask]] On Behalf Of Kathleen Bethell [[log in to unmask]]
Sent: October 29, 2009 5:43 PM
To: [log in to unmask]
Subject: going to as auxiliary?

In the sentence I am going to eat that banana, is to eat an infinitive? I want to say no, because going to is the equivalent of the modal will. Would going to be an auxiliary in this case?

Kathleen Bethell
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