Learn Finnish: Järjestäjän täytyy tarkistaa vieraslista. - The organizer must check the guest list.

With necessive verbs like täytyy (must, has to), the person who has to do the action is put into the genitive case. This is a core rule of Finnish necessive sentences. So, instead of the basic nominative järjestäjä, we use the genitive form järjestäjän.

Why is the object vieraslista in the nominative form instead of the accusative vieraslistan?

This is a special rule that learners often need to review: in necessive sentences expressing obligation (using verbs like täytyy or pitää), a total object takes the nominative form rather than the standard genitive-looking accusative. Because täytyy is the main verb here, the list remains vieraslista without the -n ending.

What would happen to the word vieraslista if we changed the sentence to just 'The organizer checks the guest list'?

If we remove the necessive verb täytyy, the sentence becomes a normal action: Järjestäjä tarkistaa vieraslistan. The subject returns to the nominative case, and the total object now takes its standard -n ending to become vieraslistan.

Could I use pitää instead of täytyy here?