Given the appointment age of most justices, 20 years and life aren't much different. Furthermore, lots of justices resign a couple years before death. RBG was practically begged to resign, but alternately believed Hillary would win and/or thought she could outlast Trump.
The idea is similar to tenure. You can do and say what you believe without influence and pressure from either party. It also dodges influence peddling preparing for leaving office. For example, in the defense department, officials will make recommendations and then leave office and profit from those same companies. If you're in office for life, this common (and almost impossible to prevent) kind of corruption becomes basically a non issue.
The federalist papers would shed light on such things, but actually reading them (and the wealth of nations)is likely to turn you into an independent who dislikes both parties.
Given the appointment age of most justices, 20 years and life aren't much different.
The last 4+ justices appointed were in their 50s. Gorsuch was 50. A top name on the short list both times was Amy Coney Barett, 48. They've been grooming a 38 year-old, Justin Walker, for the court. He went from a few months of litigation experience to the federal bench to the DC circuit in a year.
Notice how all these people also look very healthy? They're trying to get people who will last a lot longer than 20 years.
The idea is similar to tenure. You can do and say what you believe without influence and pressure from either party. It also dodges influence peddling preparing for leaving office. For example, in the defense department, officials will make recommendations and then leave office and profit from those same companies. If you're in office for life, this common (and almost impossible to prevent) kind of corruption becomes basically a non issue.
The federalist papers would shed light on such things, but actually reading them (and the wealth of nations)is likely to turn you into an independent who dislikes both parties.