In every university I've seen (in France and Japan in STEM) the Ph.D. is minimum 3 years, but many (most?) students do it in 4 because they don't have the requi

In every university I've seen (in France and Japan in STEM) the Ph.D. is minimum 3 years, but many (most?) students do it in 4 because they don't have the required publications in 3 years. It's rare, but some do it in 5. Apparently in liberal arts the Ph.D. tends to drag on an on 5, 6, 7 years... So yes, you do need a master before starting your Ph.D., and I've never heard of someone doing their Ph.D. in 2 years. Maybe if you hit a homerun and get prestigious publications very early.