Can a blind person do a post-doc in the humanities?
In the United States there's what is known as the Americans with Disabilities Act (ADA)

which prohibits discrimination based on disabilities and mandates reasonable accomodations. Full or partial blindness will definitely fall under that category, and so they are legally prohibited from discriminating against you and if hired will work with you to help out. Many other locations have similar laws. In Canada the laws vary from province to province, but most of Canada has similar laws. Many (although not all) European countries have similar laws or regulations as well.