English and the Austronesian language Mbarbaram both use the word “dog” for canines.
Conclusion (thus / this shows that)
Sometimes when languages share words that are similar in sound and meaning, the similarity is due neither to language relatedness nor to borrowing.
Evidence (since)
English and the Austronesian language Mbarbaram both use the word “dog” for canines.
The two languages are unrelated.
Speakers of the two languages came into contact only long after the word “dog” was used in either language.
Intermediate Conclusion
Therefore, neither language could have borrowed “dog” from the other.
Evaluate
It's hard to argue with the intermediate conclusion. If both languages had the word 'dog' before ever coming into contact with each other, then neither of them could have borrowed it from the other language.
But does that prove that "dog" is an example of a similar word that has nothing to due with language relatedness or borrowing?
Well, the argument establishes the languages aren't related. Can we possibly argue that the common word "dog" is related to borrowing, but just not borrowing from each other?
Goal
We want an answer that rules out the possibility of some hidden borrowing source or otherwise upholds the claim that this case is indeed an example of two languages sharing a word without relatedness or borrowing.