How do you you parse this sentence?
Here's my attempt:
comp: to be a man (infinitive)
is the whole infinitive phrase the complement or is "a man" the complement, and "to be" an expletive?
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It only takes a minute to sign up.Sign up to join this community
'It' is not always a real subject but a grammatical construct so that a sentence which does not need a subject has one, as in "It is raining." This usage is sometimes called 'dummy subject'.
Your sentence actually does not have a subject but English grammar requires a subject. So 'it' is used in lieu of a subject. (In other languages it is common to omit the subject and have the verb conjugation hint which omitted pronoun would be the subject.)
Particularly, in the copular/linking verbs as "appear" & "seem" we often use 'TO BE' for showing a relationship or describing a state. It is better to regard "seem to be" as verb phrase. "A man" is the complement.
Otherwise, "seem" may take a clause/ phrase as its complement.
° It seems that it would rain today.
°°I seem to have left my book at home.
In the last sentence "to have" is not the part of the verb phrase but part of an elliptical clause--"to have left my book at home".