ON FEB. 12, 2002, Secretary of Defense Donald Rumsfeld took the stage at a press briefing to address escalating tensions between the U.S. and Iraq. A reporter asked him a question regarding evidence of Iraqi weapons of mass destruction.
Rumsfeld famously replied, “There are known knowns; there are things we know we know. We also know there are known unknowns; that is to say, we know there are some things we do not know.

OUR PAST INVESTMENT errors give us strong clues about how we’ll behave in future. They also contain lessons we can put to good use.
Since I started investing, I’ve occasionally assessed my performance—but not in the traditional sense. Rather than evaluating my portfolio’s results, I’ve been pondering my response to the errors I’ve made.
My first mistake happened before I even began investing. I avoided the stock market because of fears of a potential correction.

MANY OF US DREAM of owning a second home near the sea, a lake or the mountains. For my wife and me, that dream location was the southern New Jersey Shore. We’d both spent many vacations there as children and then did the same with our own growing family. We had visions of taking grandkids to the beach and boardwalk.
In March 2012, we realized our dream by purchasing a three-bedroom condo in Ocean City,

I MISS BASEBALL. I love the strategy and the moments of excitement that come in the later innings. I also like to attend games, watching the interaction among the players and coaches. The third base coach plays a big role, relaying signals from the manager to the baserunners and the batter. If you’re a player, and you miss a signal, it can ruin the next play.
While the stock market has signals, they aren’t as black and white as those in baseball.

I’M THE TYPE OF PERSON who likes to plan. I have at least 10 to-do lists going at any one time. I have calendars on my refrigerator, my desk and my phone. I plan out my days, my months, my years and, on occasion, my decades.
My job, managing the biology department at a small liberal arts college, is a perfect fit for my personality. For the past 22 years, I’ve methodically planned out every day of each semester.

LAST WEEK, I TALKED about some of the unsettling trends in the financial markets. In that article, I focused on the role of brokers and day traders, and noted that it takes two to tango. But it turns out the dance floor is quite a bit more crowded than that.
Yes, brokers and day traders are doing their part, but there’s another set of actors who are less visible but a whole lot more influential.

WE DON’T PURSUE MONEY just to put food on the table and a roof over our head. Instead, the hope is to enhance our life. On that score, it seems we aren’t doing terribly well: Our reported level of happiness is no higher than it was half a century ago.
Could we do better? I believe so. There’s been extensive research on happiness in recent decades. For those who want to dig into the details,

IF YOU’VE WORKED a lifetime—while prudently saving and investing—so that in old age you’re well off financially, should you feel guilty?
If your retirement income is greater than the income of most American families, including those still raising young children and facing college costs, as well as the cost of their own retirement, is that embarrassing?
A few years back, during a discussion about how people spend, save and invest, my son-in-law—who’s a financial advisor to high net worth families—casually said to me,

I PURCHASED MY FIRST house almost 30 years ago. To call it a “fixer” would have been an understatement. It was 800 square feet of neglected space in desperate need of repairs and updating. Being fresh out of college and working at a job that paid less than $20,000 a year, I didn’t have a lot of money to spend on improvements. But I had the energy and enthusiasm of youth.
Over a five-year period,

“NICE OFFICES,” OFFERED the 30-something investor, as he cast a wary eye across the corporate art, barren desks and empty bookshelves.
“Yeah, we asked management if they could put us on the 12th floor, so our suite number could be 12b-1. Funny, right?” The financial salesman winked.
“Not sure I get it.”
“It’s a joke, but clients never get it, they pay it.”
“What qualifications do you have?”
“See those initials after my name?

IF YOU’RE MARRIED, filing for Social Security can be confusing. But there’s one group who has it even worse—those who are divorced.
In recent weeks, I’ve had a number of conversations with women who had no idea that they were even eligible for spousal benefits based on their ex-husband’s earnings record. (I also recently watched the television show Dirty John: The Betty Broderick Story, which gave completely erroneous advice on benefits for ex-spouses.) My hope: Someone reading this may learn that he or she is eligible for spousal or survivor benefits from an ex-spouse.

“THE CHINESE PLAY the long game. We play checkers, they play chess.”
You hear such sentiments from Americans a lot. It’s one of the narratives that draws foreign money to China. The story is so good, it distracts investors from an important fact: The oldest China exchange-traded fund, the iShares China Large-Cap ETF (symbol: FXI), has lost a quarter of its value since peaking in 2007. Yet somehow—helped by Chinese government pressure on index providers—China’s weight in the emerging markets indexes is higher than ever.

IN HER MOST RECENT book, former Secretary of State Madeleine Albright quotes Mussolini. “If you pluck a chicken one feather at a time,” he said, “no one will notice.”
Don’t worry, I’m not veering into political commentary. But when I heard this quote, it brought to mind what we’ve been seeing in the financial markets this year. Taken individually, there’s nothing that strikes me as a clear red flag. But taken together, the current environment looks a little bit like a chicken that—all of a sudden—seems to have lost a whole lot of feathers.

IT’S INDEPENDENCE Day. But how truly independent are we, both financially and in our thinking? The two, I believe, are inextricably entwined.
Whether it’s the TV shows we watch, the political views we hold or the investments we buy, we often take our cues from family, friends and colleagues. They, in turn, may be influenced by advertising and the media. But however ideas get spread, the result is that most of us aren’t the fiercely independent thinkers we imagine.

I’M 28 YEARS OLD. How much should I have in stocks? Some financial experts would suggest allocating 90% of my portfolio, because I have a long time horizon and a steady job. But I don’t think that would be a good idea for me.
My father has driven hundreds of thousands of kilometers over his lifetime—because he’s afraid of flying, despite the much lower risk that air travel entails. Similarly, I have a good idea of what optimal investing behavior looks like for someone of my age.