Alma suggests an experiment: believe, or at least desire to believe, something is true. If it turns out to be good, then you know it is true and worth believing; otherwise forget it. This is an approach to knowledge that is exceedingly prone to confirmation bias: the tendency to favor information that confirms preexisting beliefs or hypotheses.

The missionaries would often use this scripture to ask me to conduct various ‘experiments’ to help me recognize the manifestations of the holy spirit. Worse, they would often use methods which introduced further bias. For example they would ask me to pray by asking God if the Book of Mormon was true. They would then bear testimony that they know the Book of Mormon is true and they are sure if I’m sincere then I will come to know as well. At our next meeting they would ask me what I felt when I was reading and praying, especially did I feel good or peaceful (as if the only way I would feel peaceful while reading is if the holy spirit were speaking to me). That technique, suggesting what an investigator will feel when they pray, is prone to the observer-expectancy effect in which the missionaries' cognitive bias affects the investigator’s. It is an attempt to avoid this bias that many courts do not allow leading questions during direct examination.

Other experiments included changes to my lifestyle (praying everyday and attending church service and events). Whenever I didn’t receive a testimony of the truth of the church, the solution was to suggest more ways I could become invested in the church. One sister missionary, in all sincerity, suggested I be baptized into the church because she thought that would help me gain a testimony. I was reminded of the part of The Adventures of Huckleberry Finn when Tom is trying to convince Jim to tame a rattlesnake: “Blame it, can’t you TRY? I only WANT you to try — you needn’t keep it up if it don’t work.”

The technique of asking investigators to spend more of their time ‘experimenting’ is prone to escalation of commitment: the investigator has so much invested in the truth of the church that they will tend to believe it is true without sufficient reason.

In any case neither Moroni’s promise nor the experiment of the seed are useful in determining the truth of the church. Moroni’s promise presupposes the truth: either the investigator has it confirmed by the holy spirit, or they didn’t pray sincerely (or they just haven’t waited or invested enough yet). Alma’s experiment doesn’t test for truth, it tests whether an idea is good or not.

Note that early in the passage I quoted above Alma equates “true seed” with “good seed”. From then on he only discusses what is “good”. He even uses the metaphor of a growing plant to explain the physical feeling of swelling emotions which occur when an idea is good. This is the prophet complex! Alma 32 contains insight into the internal justifications of a pious fraud. It seems likely to me that in Joseph Smith’s mind if an idea felt good enough after consideration, then it also passed the test of truthfulness. Indeed many members of the LDS church, the so-called Cultural Mormons, are members precisely because they believe the church is good though not necessarily true. While interesting, it is not a path to knowledge I would take for myself and I do not consider Mormonism to be on firm epistemological ground.