One should always capitalize the main words and the first and last words of a title.
Facts
conditionals (always, never)
Main word of title → should capitalize First or Last word of title → should capitalize
Article / prep / conj < 5 LTRS and → shouldn't capitalize Occurs in middle of title
Evaluate
The #1 thing we read for on MBT is conditionals. We have two of them here. Do they chain together?
No, they sort of outline different rules for different words in a title. We end up feeling like we know which words we should / shouldn't capitalize, other than for prepositions / conjunctions 5 letters or longer. They don't qualify under the rule that says can't capitalize. And (unless we'd call them a "main word"), they don't qualify under the rule that says must capitalize.
So it seems like we have some freedom there to capitalize or not capitalize.
Goal
No way to know where this is going, so just find the most provable answer.