The God of Abraham, Isaac, and Jacob is not a god of ignorance and whim. He is the God of reason. He does nothing arbitrarily. Our interactions with him are not mere pleadings for arbitrary favor, but requests for what is accordant with reality and his divine justice.
Because there is opposition in all things (see 2 Nephi 2:11), the existence of reasons in support of something is insufficient to gain perfect confidence in that thing. There will always be one or more reasons to support anything you can think of. The existence of supporting evidence is irrelevant. What matters is how the rational arguments of each option stack up in comparison to each other—stronger reasons are better than weaker reasons. Reasons supporting competing alternatives must be weighed against each other. What is right is clear not because it exists without opposing alternatives, but because, when adequate effort and skill is invested in reasoning through available information, a clear winner emerges.
Comparisons are also required between the reasons and the purported outcome—bigger risks are justified for bigger reward; stronger reasons are required for less likely outcomes, and so on.