You will never disprove a conspiracy a priori. I think that what you need to do is ask them what the best evidence for a conspiracy is, and then provide a ratio

You will never disprove a conspiracy a priori. I think that what you need to do is ask them what the best evidence for a conspiracy is, and then provide a rational explanation that does not require a conspiracy. Them, go down the list of suspicions that they have and do the same.