... witches must exist because, after all, everyone believes in them. Anything that a large number of people believe must be true.
Of Credulity and Incredulity, (1668) Meric Causabon
"The raising of storms by witches is attested by so many, that I think it needless to recite them."Certainty of the World of Spirits, (1691) Richard Baxter
..... "why that 'tis impudence to deny it." *
* I may have taken the second part of this quote out of context (I can't find the full text) but I think the point is the same