When a Caltech student asked the eminent cosmologist Michael Turner what his "bias" was in favoring one or another particle as a likely candidate to compromise dark matter in the universe, Feynmann snapped, "Why do you want to know his bias? Form your own bias!"
Perfectly Reasonable Deviations from the Beaten Track: The Letters of Richard P. Feynman (ed. Basic Books, 2006) - ISBN: 9780465023714