Plato puts the following words into the mouth of Simmias in The Phaedo:
It seems to me, Socrates . . . that to know anything certain about such things [as the immortality of the soul] in this life is either impossible or exceedingly difficult, but to give up without completely testing the views on the subject and before you’re totally exhausted from examining them on every side is the mark of a weakling.
For we must accomplish one of the following: either learn the truth about this from someone else or find it out for ourselves, or if that’s impossible, at least catch the best most irrefutable human argument we can find and ride on it like a raft, sailing through life taking our chances on it, unless we can get safer, less dangerous passage on a securer vessel in the form of some divine explanation. (85c-85e, tr. Raymond Larson)