We’re all getting older, of course. But we’re not talking about individuals here. It’s the average age of bank CEOS that’s rising fast. In 1998, community bank CEOs in the D.C. area averaged 49 years of age. In 2011, that average was 56. That is not a sustainable curve. And there’s every indication that this is par for the course nationally as well.

That means an avalanche of retirements is coming to financial services in the next decade. And the question of who will replace these leaders has many in the industry losing sleep.

A lot of the CEOs in community banking today learned the ropes in extensive management training programs, spending as much as two years in the trenches learning every job in the bank. But starting with the banking crisis of the early 90s, many smaller banks ditched management training programs to save money, shifting instead to a sales-driven culture. As a result, many of the younger managers lack the critical thinking skills that such programs gave the older generation of leaders.

It all adds up to a nightmare for succession planning. That’s why research by the Miles Group shows that executive development is a top concern for CEOs. The bench is just too shallow. As so many leaders move toward retirement, too few junior executives are ready for the next tier.

The recession didn’t help one bit. Many of the skilled lenders and strategists stayed on to take banks through the recession, but they were so busy fixing things that they didn’t spend time developing the next generation. Now there’s a big gap in competencies, and for those who close that gap, it’s going to be one of the most meaningful predictors of future growth and profitability.

A mentor of mine, who serves on the executive committee of the tenth largest financial institution in the world, confirms this particular worry. He told me that for many years when he hired, he looked at attitude first and foremost. A good attitude is imperative; there’s no doubt about that. But he came to realize that solid critical thinking skills are even more important—and all too rare in business today. He calls it “uncommon sense.”

The cause of the problem goes well beyond the industry itself. One 2013 study showed that students in America currently have absolutely no increase in critical thinking skills after four years of college. Whoa! Employers are outraged because they feel they can’t find people with the critical thinking skills needed to fill their positions.

Developing critical thinking skills is Job One in leadership development today. That’s why critical thinking has become a kind of buzzword in business. Everybody wants it, and everybody says it’s important. But most banks are stopped cold before they start because they don’t even know what critical thinking is.

Ask someone what critical thinking means, and they’ll usually say, “You know…being a good thinker.” What in the world does THAT mean? Or even worse, they’ll say, “Critical thinking means being smart.”

A critical thinker is someone who learns and uses skills that make for organized, disciplined thinking. It’s not about what you know—it’s about HOW you think.

Business decisions, especially in the C-suite, require a careful, systematic process that anticipates errors and avoids them. And the biggest obstacle to that critical process is something called confirmation bias—the tendency to see things the way we prefer instead of the way they are.

We all have a tendency in business to give an overly rosy report of our own pet projects, ignoring any shortcomings or casting them in the best possible light. And when someone fills out their own performance review, they often don’t know what they don’t know, which is why BusinessWeek’s study revealed that over 90 percent of people think they perform in the top 10 percent.

The opposite of critical thinking is reactive thinking— the kind of automatic, unexamined thinking we all do.

Reactive thinking isn’t always bad. You don’t want to stop and ponder your options when the traffic light turns red. You want to react. If something comes flying at your head, react! But when it comes to deciding whether to take a job, how to vote, whether to buy that stock, or whether to eat those yummy-looking wild mushrooms—that’s when you need a systematic process that helps to avoid errors in reasoning. Same with just about every decision made in upper management.

Executives don’t pull levers without thinking of consequences—the stakes are too high. If you are a mid-level executive looking to move up into the looming leadership vacuum in your bank, learn to anticipate the outcomes of your decisions and to weigh out in every case what the best-case scenario is, what the worst-case scenario is, and what the likely scenario is from your decision. That process will serve you well as you make far more enlightened and valuable decisions.

Finally, institutions themselves need to have succession plans in place, building the right capabilities and comprehensions at every level, including:

• understanding management accountability
• knowing that marketing is not just a department, but a way of thinking that everyone must have to constantly increase the quality of customers
• understanding that sales is a system and that it’s integrated with marketing
• understanding that performance management is about understanding how to tie everything together with the strategic, quarterly, and weekly plans

…and much more.