If: Aliens = Extra-terrestrial, sapient, material beings that 'evolved' somewhere on another planet out in space. John Dee's diary describes spiritual encounters and rituals in some detail, and Alistair Crowley conjured "Lam" which was essentially a "Grey," why should I trust extra-terrestrial accounts and not Bigfoot ones? Especially when both have the same issues, like UFOs defying the laws of physics and Aliens passing through solid objects like a ghost, or Bigfoot not leaving any physical tracks/ traces, not impacting the local ecosystem. "Aliens" as in "Foreigners"- absolutely.