Priors and Surprise

I don’t want to be too dog­matic about this claim, but Godzilla is un­re­al­is­tic. I don’t want to be too non-dog­matic about this claim ei­ther. OK then, just how dog­matic should I be? I have all sorts of rea­sons for think­ing that skyscraper sized lizards or dinosaurs don’t ac­tu­ally ex­ist. Hon­estly, the most im­por­tant of these is prob­a­bly that none of the peo­ple who I imag­ine would know if they did ex­ist seem to be­lieve in them. I never hear any men­tion of them in the news, in his­tory books, etc, and I don’t see their effects in the na­tional death statis­tics. No in­dus­tries seem to ex­ist to deal with their ram­pages, and no oil or ship­ping com­pa­nies lose stock value from lizard at­tacks. Ca­su­ally, at least, Godzilla at­tacks don’t seem like the sort of ba­sic fact about the world that peo­ple could just over­look. How con­fi­dent should I be that Godzilla type crea­tures don’t ex­ist?

I can also fairly eas­ily rec­og­nize good biolog­i­cal rea­sons not to ex­pect there to be gi­ant ram­pag­ing lizards. The square/​cube law, in its many man­i­fes­ta­tions, is the most ba­sic of these, but by it­self is not com­pletely de­ci­sive. I can imag­ine phys­i­cal workarounds that would al­low se­quoia gi­gan­ti­cus sized rep­tiles, but not with­out novel bio-ma­chin­ery that would take a long time to evolve and would surely be found in many other or­ganisms. I can even vaguely imag­ine ways in which biol­ogy might prove re­sis­tant to con­ven­tional mil­i­tary weaponry and ecolog­i­cal niches and lifestyles that might sup­port both such biol­ogy and such size, though much of my knowl­edge of Earth’s ecosys­tems would have to be re-writ­ten. For all that, if I lived in a world where es­sen­tially all au­thor­i­ties did re­fer to the ac­tivi­ties of godzilla gi­gan­ti­cus I would prob­a­bly ac­cept that they were prob­a­bly cor­rect re­gard­ing its ex­is­tence. What should a hy­po­thet­i­cal per­son who lived in a world where the ex­is­tence of Godzilla type crea­tures was com­mon knowl­edge and was re­garded as an or­di­nary non-nu­mi­nous fact about the world be­lieve?

Godzilla would be con­sid­er­ably more per­plex­ing than thun­der­stones, and would have to be con­sid­er­ably bet­ter doc­u­mented to be cred­ible. Even with the strongest doc­u­men­ta­tion I would have sub­stan­tial un­re­solved ques­tions, in­fer­ring that Godzilla’s na­tive ecosys­tem must be quite differ­ent from any known (pos­si­bly in­fer­ring that the de­tails are clas­sified), and even won­der­ing whether Godzilla was a biolog­i­cal crea­ture at all as op­posed to, for in­stance, a gi­ant robot left be­hind by an ad­vanced and for­got­ten civ­i­liza­tion, a line of in­quiry that would greatly in­crease my cre­dence in se­cret his­tory of all kinds. For the most part though, I would prob­a­bly go about life as nor­mal. Even Nat­u­ral Selec­tion, the most dam­aged part of my world-view, would en­dure as a great in­tel­lec­tual triumph ex­plain­ing the ori­gins of al­most all of Earth’s life forms. Only periph­eral facts, such as dis­tant his­tory and the na­ture of some ex­otic ecosys­tems would be deeply called into ques­tion, and such facts are not tightly in­te­grated with the broader ed­ifice of sci­ence. In a con­ver­sa­tion with a hy­po­thet­i­cal Michael Vas­sar who be­lieved in Godzilla, the is­sue would typ­i­cally not come up. Science in gen­eral would not be called into ques­tion in my mind, but should it be?