Re: The roles of the various that's in the sentence:

        That that that that man ate was poisonous shocked Max.

Martha Kolln wrote:

>Dick:
>
>This is so easy to illustrate with a traditional diagram!
>
>(1) The first that is what I call an expletive--i.e., the that that
>introduces a nominal clause (in this case, the clause as subject of
>shocked);  some linguists call it a nominalizer; (in a simpler sentence it
>would read "That the mushroom was poisonous shocked Max)
>(2) the second that is a demonstrative pronoun, the headword of the noun
>phrase that is the subject of shocked; it's a noun phrase (or, in this
>case, pronoun phrase) with one post-pronoun modifier, a relative clause);
>(3) the third that is, indeed, a relative pronoun, direct object of the
>verb ate in the relative clause; the clause is "that man ate that";
>(4) the fourth is the demonstrative pronoun that, functioning as a
>determiner for the subject headword man in the relative clause--i.e., that
>man.
>
>A traditional diagram would clear this up in no time flat!
>
>Martha Kolln

Martha:

As usual, you are faultless and win a very honorable mention.

I'd also call #1 a "complementizer" or "complementizing conjunction" since
it introduces a complement clause.  I'd also call #4 a "demonstative
determiner" to distinguish it from the strictly pronominal use of the
demonstrative in #2.

I can't help adding that a tree diagram would also easily clear this us
(and label all the parts, to boot!).  I posted it in case you'd like to see
it:

        http://www.uncwil.edu/people/veit/DEG/That_that.htm

Dick