Questions & Answers about Ég er sammála sumum, en ekki öðrum.
Why are both sumum and öðrum in the dative case here?
The word sammála (agreeing) dictates the case in this sentence. Whenever you are in agreement with someone or something, that person or thing must be in the dative case. Because you are agreeing with some and others, both of those pronouns take the dative plural ending.
Is sammála a verb, just like the word agree is in English?
No, in Icelandic sammála is actually an adjective that means being in agreement. That is why you have to use it with the verb vera (to be), as in ég er sammála (I am in agreement). A nice bonus is that sammála never changes its ending, regardless of who or how many people are agreeing!
What is the base form of öðrum, and why does it look so different from it?
The base dictionary form is annar (other). This pronoun goes through some major spelling changes depending on its role in the sentence. When it takes the dative plural ending -um, the a in the stem changes to an ö, and the double n turns into ðr, resulting in öðrum.
Do sumum and öðrum reflect a specific grammatical gender here?