Learn Hardcore Greek: Είναι δίκαιο να έχεις τη δυνατότητα να επιστρέψεις ένα ρούχο που δεν είναι κατάλληλο, ιδιαίτερα όταν δεν μπορείς να το δοκιμάσεις στο δοκιμαστήριο. - It is fair to have the option to return a piece of clothing that isn't suitable, especially when you can't try it on in the fitting room.

Yes, in this sentence να is roughly equivalent to English “to” before a verb, but grammatically it marks the subjunctive mood, not an infinitive. Modern Greek has no infinitive, so it uses να + verb instead:

να έχεις – to have
να επιστρέψεις – to return
να δοκιμάσεις – to try (on)

So να introduces a subordinate clause and puts the verb in the subjunctive, which is used for possibilities, wishes, obligations, etc.

Why are there two να’s in να έχεις τη δυνατότητα να επιστρέψεις?

Because there are two separate subordinate clauses:

να έχεις τη δυνατότητα – to have the possibility
να επιστρέψεις ένα ρούχο – to return a piece of clothing

The structure is:

Είναι δίκαιο [να έχεις τη δυνατότητα [να επιστρέψεις ένα ρούχο…]]

The first να goes with έχεις (to have), and the second goes with επιστρέψεις (to return). Each να marks its own verb in the subjunctive.

Why use τη δυνατότητα and not just μπορείς (you can)?

Both are possible, but the nuance is different.

μπορείς να επιστρέψεις – you can return / you are able to return
έχεις τη δυνατότητα να επιστρέψεις – you have the possibility / the option to return

Using the noun δυνατότητα (possibility, opportunity, option) makes it sound a bit more formal and abstract, stressing the right or option rather than simple ability.

Also note the article:

τη δυνατότητα – literally the possibility, but in English we normally say just the possibility or the chance; using the definite article here is very natural in Greek even in a general statement.

Why is it να επιστρέψεις and not να επιστρέφεις?

The difference is aspect:

επιστρέψεις → aorist subjunctive (single, complete action)
to return (one time, as a whole act)
επιστρέφεις → present subjunctive (ongoing, repeated action)
to be returning / to return repeatedly

Here, you’re talking about one act of returning a clothing item, not returning clothes again and again as a habit, so Greek prefers the aorist να επιστρέψεις.

If you said:

να επιστρέφεις ρούχα συνέχεια
it would suggest to keep returning clothes all the time (repeated action).

Why is it ένα ρούχο (singular) and not ρούχα (plural), when in English we often say “clothes”?

Greek ρούχο means “item of clothing / garment”, and it is perfectly normal to use the singular in a general statement:

να επιστρέψεις ένα ρούχο που δεν είναι κατάλληλο
to return a piece of clothing that is not suitable

If you wanted to talk explicitly about multiple items, you could say:

να επιστρέψεις ρούχα που δεν είναι κατάλληλα – clothes that are not suitable

But the singular ένα ρούχο here is generic: a garment, any garment that turns out not to be suitable.

Why is the relative pronoun που used in ρούχο που δεν είναι κατάλληλο, and not ότι or ο οποίος?

In modern spoken Greek, που is the default relative pronoun for “that / which / who”:

ένα ρούχο που δεν είναι κατάλληλο
a piece of clothing that is not suitable

ότι introduces content clauses (that… in “I think that…”, “He said that…”), not relative clauses:

Ξέρω ότι δεν είναι κατάλληλο.
I know that it is not suitable.

ο οποίος / η οποία / το οποίο is a more formal and heavier-sounding relative pronoun:

ένα ρούχο το οποίο δεν είναι κατάλληλο – grammatical but more formal.

So που is the natural, everyday choice here.

What exactly does κατάλληλο mean here?

κατάλληλο means “suitable, appropriate, fitting, right (for the purpose)”.

In the context of clothing, it can imply several things:

Not the right size
Not the right style or color
Not appropriate for the occasion

It agrees in gender, number and case with ρούχο:

ένα ρούχο (neuter singular) → κατάλληλο (neuter singular)

In δεν μπορείς να το δοκιμάσεις, what is the το, and why is it needed?

το is the direct object pronoun meaning “it”, referring back to το ρούχο.

να δοκιμάσεις το ρούχο – to try on the clothing item
να το δοκιμάσεις – to try it (on)

Greek almost always keeps such object pronouns when the noun has already been mentioned, especially when the noun itself is omitted. Without το, να δοκιμάσεις would sound incomplete here, because you no longer say το ρούχο explicitly.

Also note the position: the weak object pronoun normally goes before the verb in this kind of structure (το δοκιμάσεις), not after.

What is the difference between δοκιμάζω and other verbs for “try”, and why δοκιμάσεις here?

δοκιμάζω means:

“to try, to test, to try on (clothes, shoes, etc.)”

It is exactly the verb used for trying on clothes:

δοκιμάζω ρούχα / παπούτσια – I try on clothes / shoes.

Here we have δοκιμάσεις, which is the aorist subjunctive:

να το δοκιμάσεις – to try it (on) once / as a complete action

Again, the aorist is used because this is a single act of trying on the garment, not a repeated or ongoing activity.

Why is it στο δοκιμαστήριο and not just σε δοκιμαστήριο?

στο = σε + το (in + the).

δοκιμαστήριο means “fitting room / changing room”, and Greek normally uses the definite article in such contexts:

στο δοκιμαστήριο – in the fitting room

Even when English might say just “in a fitting room” in a general sense, Greek often still prefers the article:

Δεν μπορείς να το δοκιμάσεις στο δοκιμαστήριο.
Literally: You can’t try it on in the fitting room.
Meaning: You can’t try it on in (the) fitting room(s) / there is no opportunity to use a fitting room.

σε δοκιμαστήριο (without the article) is possible but would sound more like in some fitting room or other, less natural here.

What is the role of ιδιαίτερα in ιδιαίτερα όταν δεν μπορείς να το δοκιμάσεις…? Could it go somewhere else?

ιδιαίτερα means “especially, particularly” and modifies the whole when-clause:

… ιδιαίτερα όταν δεν μπορείς να το δοκιμάσεις στο δοκιμαστήριο.
… especially when you can’t try it on in the fitting room.

You could move it slightly:

… όταν ιδιαίτερα δεν μπορείς να το δοκιμάσεις στο δοκιμαστήριο. – possible but less natural.
Είναι ιδιαίτερα δίκαιο να έχεις τη δυνατότητα… όταν δεν μπορείς… – now ιδιαίτερα modifies δίκαιο (especially fair).

In the original sentence, ιδιαίτερα right before όταν is the most natural and clear place to say:
This is fair, *especially in the situation when you can’t try it on.*