It's a bit of a different path to yours and probably substantially less interesting. Science, theory, probability and logic are my foundations. Studying things like the Drake Equation and Bostroms Trilemma and looking at the pace of our own species rapid development in the context of the age of our planet, solar system, galaxy etc and accepting that any other species out there would either be millions of years more advanced (incomprehensible to us) or they'd be amoebas.