This is from Noah Smith:

Harvard's Greg Mankiw, author of the most popular college introductory economics textbook, is often regarded as America's econ teacher. He famously refers to his "Principles of Economics" as "my favorite textbook," and I must admit that it's also my favorite. It's written in a clear, explanatory style and covers the basics of most important theories in modern economics. 

But Mankiw's book, like every introductory econ textbook I know of, has a big problem. Most of what's in it is probably wrong. 

In the last three decades, the economics profession has undergone a profound shift. The rise of information technology and new statistical methods has dramatically increased the importance of data and empirics. This means that many professional economists are no longer, as empirical pioneer David Card put it, "mathematical philosophers." Instead, they are more like scientists, digging through mountains of evidence to find precious grains of truth. 

This is actually quite true. When teaching my students Economics, I always remind them that what they learn in JC are just the simplest, non-mathematically demanding models, and that real life is usually a lot more complicated than that. I challenge them to read up more on empirical data that can help enhance their understanding of the theories they learn in school, and pick out on some of the simplistic thinking and communications to the public that even supposedly well trained policy makers in Singapore tend to indulge in.