12 Looking at the noun basis on Wiktionary.com, it indicates that the plural is either bases or baseis. It looks like the rare baseis comes from the Greek, but the common bases just refers back to basis and that does not explain the plural etymology.
The plural of “basis” is “bases”. “Bases” is also the plural of base. One of the standard rules for forming the plurals of nouns in English is: Nouns ending “is” - change the “is” to “es” The noun “basis” adheres to this rule. Apparently “baseis” is the Greek plural of the Greek word “basis” not the English version, even though the origin of the word is ...
Even if you have several factors contributing individually and severally to one or more conclusions, use basis -- the reference is to the relationship, not the individual contribution (s) at all. 'Candidates (several) may be screened on the basis of their (plural) age, qualifications, experience and potential (several)'.
There are many plural rules for nouns. Discover the most important ones and learn how to put them into practice with this guide.
It appears to be a common mistake: The singular “woman” probably gets mixed up with the plural “women” because although both are spelled with an O in the first syllable; only the pronunciation of the O really differentiates them.
The "rationale" is the set of principles which underpin some argument. In this respect, using "rationales" as a plural to explain a single item (i.e. the belief mentioned in the example) is incorrect, as the "rationale" (singular) can include multiple "reasons". I would simplify it by using "reasons" in the sentence above, or rewrite it to indicate that the rationale includes multiple reasons ...