Breakdown of Hän tuntee itsensä sekä riittämättömäksi että arvottomaksi.
hän
he / she
että
that (conjunction)
itse
self, oneself
sekä
both
Questions & Answers about Hän tuntee itsensä sekä riittämättömäksi että arvottomaksi.
Why are the adjectives riittämättömäksi and arvottomaksi in the translative case ending in -ksi?
This is the core of the tuntea itsensä (to feel oneself) structure. When you describe how you feel using this verb phrase, the adjective describing the feeling must be in the translative case. Even though the translative often implies a change or becoming something, with this specific verb it simply expresses the state or quality you perceive yourself to have.
Could I use the tuntuu structure instead to say this?
Yes, but the grammar changes entirely! A very common B2 trap is mixing them up. If you use the verb tuntua, the person feeling it takes the elative -stä ending (Hänestä tuntuu...) and the adjective takes the ablative -lta/-ltä ending (...riittämättömältä ja arvottomalta). Because this sentence uses tuntea (an active verb meaning to feel or sense), it strictly requires the reflexive pronoun itsensä as the object and the translative case for the adjectives.
How do the base words of riittämättömäksi and arvottomaksi break down?
Both adjectives are built using the suffix -ton/-tön, which means 'without' or '-less'. Arvoton comes from the noun arvo (value) plus -ton, meaning 'worthless'. Riittämätön comes from the verb riittää (to be enough) in its negative participle form, literally meaning 'un-sufficing' or 'inadequate'.