How to parse the grammar of a sentence that appears to have two tensed verbs

This question came from a student of mine - he wanted to know how to parse the grammar of this sentence, which appears to be simple but clearly is not:

• Peter seems to have found his glasses.

Sentences of this form are very common in English but the syntax is puzzling. The main verb is clearly seems, usually a link verb, so the basic syntax ought to be:

Subject + Link Verb + Subject Complement S+LV+SC

But the verb phrase to have found appears to be tensed (present perfect), and the meaning delivered is similar to the the tensed form (he found them and they are still found). But this verb phrase can not be tensed and does not agree with the subject (if it did it would be has found). It has to be a verb complement.

Now, the rule for subject complements is generally that they are either an adjective phrase or a noun phrase, but this complement is neither, and yet it clearly is describing the subject.

So the question is - how do we parse this?

Other sentences with the same form follow:

• The answers given seem to have addressed your question adequately.
• I am lucky to have found this site.
• The library seems to have closed.

So, what is the best way to parse the grammar of sentences like these?

Solution 1:

How to parse the sentence is not simple. First, it is not a simple sentence. It has two clauses, each with a main verb. The matrix verb is seem, and it is tensed. The rest of the sentence is part of the subordinate infinitive clause, whose main verb is find. But infinitives don't have tense, so it is not a tensed verb.

The logical structure of the actual sentence is something like

• *seem* (PAST (*find* (*Peter*, *his glasses*)))

which means, roughly that some past event of Peter finding his glasses appears (to the speaker) to have happened. That is, the infinitive clause

• (for Peter) to have found his glasses

is the subject of the verb seem. English does not allow that construction, however:

• *For Peter to have found his glasses seems.

Instead, English requires either the rule of Extraposition, which puts in a dummy it as subject, and requires a that-clause:

• It seems that Peter has found his glasses.

Or it requires the rule of Subject-Raising, which has applied here, moving Peter, the subject of the subordinate clause, up to become the supposed subject of seem:

• Peter seems to have found his glasses.

Raising requires an infinitive complement, which is of course not tensed.

Solution 2:

Peter seems [to have [found his glasses]].

is a catenative construction. Verbs like "seem" and "have" are catenative verbs, a class of verbs defined as those that have a non-finite clause as complement (with a few exclusions, e.g. those where the clause is complement to be in its ascriptive or specifying senses). Examples include:

You seem to like her; I regret doing it; We arranged for them to leave; I want you to read the document

In your example, "seem" is a catenative verb and the non-finite infinitival clause "to have found his glasses" is its catenative complement.

Further, "have" is also a catenative verb and the non-finite past-participial clause "found his glasses" is its catenative complement.

In the matrix clause, "Peter" does not have a direct semantic relation with the verb "seem". The meaning is very close to "Peter seemingly found his glasses", where we have the adverb "seemingly" instead of the catenative verb "seem". Syntactically, the subject "Peter" is located in the matrix clause, but semantically it belongs solely in the subordinate clause. "Peter" is thus called a 'raised' subject because the verb it relates to syntactically is higher in the constituent structure than the one it relates to semantically.

The term 'catenative' comes from the Latin word for "chain", which is appropriate here since "seem", "have" and "find" do indeed form a chain of three verbs.

The construction is not limited to sentences containing just one catenative verb/complement, for it is repeatable in a way that enables us to form a chain of verbs in which all but the last have a non-finite complement. Take this example:

She seems to want to stop trying to avoid meeting him.

Here, each of the verbs in bold has a non-finite clause as complement.

Solution 3:

The phrase to have found is not a verb phrase, but a dependent infinitive, which does not have tense. In a limited way, an infinitive can, however, be marked for time relative to the tense of the finite verb, that is, the verb agreeing with the subject. The English infinitive has two forms: present (to go) which indicates more or less concurrent action, and perfect (to have gone), action prior to the tense of the main verb.

He seems to have found his keys.

Finding something obviously has to come before any awareness of the action, so the perfect infinitive is the only choice. This holds if that moment of awareness comes in the past:

He seemed to have found his keys.

The perfect infinitive expresses relative time regardless of the tense of the finite verb.

That was a great tribute to a teacher who seems to have had a major influence on your journey, and I applaud your courage in recounting your positive experiences with him. — Medium.com, 6 May 2019.

While the teacher’s influence may continue in the present in some fashion, a direct influence is in the past. Acknowledging the teacher’s role is in the present, thus the use of the perfect infinitive.

He was supposed to have arrived back in Dayton by Sunday evening. Unfortunately for him, he didn't arrive back until Monday evening. — Ronny Lambert, Reversed the Curse, 2009.

Here, the choice of present or perfect infinitive is dictated by the author’s wish to make the difference between planned and actual arrival more topical. Ordinarily, one would hear:

The train was supposed to arrive at ten, but there was a 45 minute delay.

In most cases, neither logic nor topicality requires the perfect infinitive:

He was different from the other boys, who seemed to be afraid of their parents— they at least showed respect. Gary, however, seemed to have his own rules when it came to respecting others. —Garlena L. Hines, I Am Not a Mistake, I Am Meant to Be, 2007, 17.