Can you use old newspaper as attic insulation?

Your dad's actually onto something real here. Blown-in cellulose insulation is legit and still used today - it's made from shredded recycled paper treated with fire retardants, so it's way different from just stuffing raw newspaper in there. It genuinely works as insulation because paper has decent R-value and fills gaps well, plus it's environmentally friendly. That said, loose newspaper by itself would be pretty sketchy for attic work since it compacts over time, can shift around, and isn't treated for fire safety, so if you're thinking DIY with old papers, skip it and go with actual cellulose if you want something comparable to what your dad installed.