How do you best evaluate a conspiracy theory? Do you think is it plausible? what evidence is there? can it be tested, disproved? is it orthogonal with my beliefs? Say we take the idea that the fingerprint unlock data on mobile phones is being harvested by governments and used in illegal databases. Yes, it is plausible, given Snowden's disclosures about government but there is no evidence. So perhaps it is put on hold or expert opinion sought. But importantly, just being aware of the possibility, may also alter behaviour, just in case. Take another. Most mobile phones have a notification LED. Iphones never have and Apple have oddly refused to include one. Is this because people are thus required to pick up and check their Iphones many times a day, thus becoming habituated? This one is less clear, it fits with a distrust of the motives of large corporations but here there are other plausible explanations. In comparison, the UFO conspiracy is a paradox. It is attractive because there is strong evidence in that there are 100 trillion worlds out there. But there is an equally strong conflicting lack of any physical evidence. So how to weigh these things, what's the best approach?