That's a rule, not an exception

We've all heard the saying about the exception that proves the rule, perhaps to the point of weariness. Personally, this has always struck me as nonsensical. How can an exception possibly prove a rule? Logic dictates the opposite: the rule is inherently flawed if there's an exception. It's as simple as that. The phrase once held a different meaning, lost to time. The problem is that this saying is often trotted out as a justification when people have accepted a principle in theory only to violate it. I often come across this in discussions about investment decisions. Nowadays, many mutual fund investors are well-versed in the best investing practices. The problem is that their actual investment portfolios often read like a catalogue of exceptions to these very practices, each justified by the infamous' exception that proves the rule' story. Suggested read: Fun vs fundamentals Consider a fundamental tenet of investing: one should never invest in an equity fund all at once. The prudent approach is to invest through SIPs, whose benefits