Struck with a belief in Alien presence

Re­cently I’ve been struck with a be­lief in Aliens be­ing pre­sent on this Earth. It hap­pened af­ter I watched this doc­u­me­nary (and sub­se­quently sev­eral oth­ers). My feel­ing of be­lief is not par­tic­u­lar in­ter­est­ing in it­self—I could be lu­natic or oth­er­wise psy­cholog­i­cal dys­func­tional. What I’m in­ter­ested in know­ing is to what ex­tend other peo­ple, who con­sider them­selves ra­tio­nal­ists, feel be­lief in the ex­is­tence of aliens on this earth, af­ter watch­ing this doc­u­men­tary. Is any­one will­ing to try and watch it and then re­port back?

Another ques­tion aris­ing in this mat­ter is how to treat ev­i­dence of ex­traor­di­nary things. Should one re­quire ‘ex­traor­di­nary ev­i­dence for ex­traor­di­nary claims’? I some­how feel that this no­tion is mis­guided—it dis­crim­i­nates ev­i­dence prior to ob­ser­va­tion. That is not the right time to start dis­crim­i­nat­ing. At most we should as­cribe a prior prob­a­bil­ity of zero and then do some Bayesian up­dat­ing to get a pos­te­rior. Hmm, if no one has seen a black swan and some bayesian think­ing per­son then sees a black swan a) in the dis­tance or b) up front, what will his a pos­te­rior prob­a­bil­ity of the ex­is­tence of black swans then be?