How to identify "deictic center" for distinguishing "come" & "go"?

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My question is:

How to identify "deictic center" for distinguishing "come" & "go"?

Let say I am at home & I say "I am going to the zoo this evening", so the "deictic center" in this case is my home & I move away my "deictic center".

But let say my friend Tom & I currently at my home & Tom said "Are you Coming to the zoo to see the lion?" & I said "Ok, I am coming to the zoo this evening". So, the "deictic center" in this case is "the zoo" & we move towards the "deictic center" (ie the zoo).

It feels like it is very arbitrary.

Note: See this link, it said the selection of "deictic center" could be due to sympathy & politeness.

Solution 1:

When you want an answer to a question, don't look randomly on the internet and expect enlightenment. Especially not for a question on language.

This random extract tries to stuff way too many possibilities into one paragraph. One gets the impression that the author is compressing a complicated phenomenon and scanting on details, which is in fact correct.

If you really want to know what deixis is about, go to the source. Fillmore's 1971 Santa Cruz Deixis Lectures are the basic documents of and the clearest statement of the study of deixis in English.

In particular, Lecture 5, "Coming and Going" deals with precisely this problem, in detail. And with many more, and much better-chosen, examples to make clear what's going on.