General rules in English for stresses are...
- One word has only one stress. (One word cannot have two stresses. If you hear two stresses, you hear two words. Two stresses cannot be one word. It is true that there can be a "secondary" stress in some words. ...
- We can only stress vowels, not consonants.
Which would make it ARR-ti-fi-sir. There are some
other rules but that seems to fit them best.
I'm...not sure who declared that words cannot have two stresses, since I've been using dictionaries for
many years that use both a primary stress mark ( ˈ ) before the primary stress syllable, and a secondary stress mark ( ˌ ) before any secondary stressed syllables, for English pronunciations. For example, from Dictionary.com, the word "syllabify" is marked as having one primary stress and one secondary stress in IPA symbols: / sɪˈlæb əˌfaɪ /, in colloquial spelling "si-LOB-uh-FIE."
Now, I would absolutely grant that a word cannot have two
primary stresses, but secondary stress is pretty damn well demonstrated in actual English usage. I would very much disagree with the claim that secondary stress is
always dramatically smaller. It is, in general, consistently a meaningful step down, but for very long words--or words that are built up from several components with different stress rules--the end result often makes at least one secondary stressed syllable closer to the primary stressed syllable. And, as syllabify shows, secondary stress can occur in words as short as four syllables--I imagine it could even occur in words as short as three, though I suspect that would be pretty rare.