Age can dull judgment — but Munger spent decades demonstrating that it doesn't have to.
Cognitive decline with age is real and should be planned for, but its pace is not fixed — a mind kept in constant use, fed with new problems and new reading, erodes far more slowly than one left idle.
Normal aging brings gradual changes to processing speed, memory recall, and sensory input.
Raw processing speed and working memory tend to decline earliest, while accumulated judgment and pattern recognition can remain strong much longer if exercised.
The result is not uniform loss but an uneven mix — sometimes sharper judgment paired with slower processing — which makes self-assessment and succession planning genuinely difficult.
Charlie Munger remained an active public commentator on investing, business, and psychology until shortly before his death in November 2023, at age 99. Colleagues and journalists repeatedly noted his continued sharpness in interviews and shareholder meetings, which he attributed to decades of deliberate, continuous reading and learning.
Beginning in 1986, epidemiologist David Snowdon's long-running Nun Study followed a group of Catholic sisters into old age, examining lifestyle, linguistic ability early in life, and later cognitive outcomes. The research became one of the most cited bodies of evidence linking sustained mental engagement to better-preserved cognitive function in old age.
Disputes over aging business leaders' mental competence have played out publicly in court — most notably the legal battle over media mogul Sumner Redstone's cognitive capacity in 2016, which exposed how corrosive it can be for an organization when succession planning and independent competence review are put off too long.
Build succession triggers and independent competence reviews into leadership roles before they're needed, not after a crisis.
02Keep learning deliberately — new subjects, new problems, new reading — rather than coasting on past expertise.
03Distinguish between the kinds of judgment that tend to hold up well with age and those that don't, such as processing speed and short-term recall.
04Invite trusted outsiders to flag changes in judgment that the person experiencing them may not notice.
05Plan handoffs as a normal part of a long career, not as an admission of failure.
Munger's own life was arguably the best rebuttal to the tendency that bears this name — proof that a mind used hard and often can stay remarkably clear for remarkably long.