Still, he said there's a big difference between going into a deal thinking it can work, and going in convinced that it will work. "It's important to have an expectation that it could fail, and to have something in place if it does," Dao says.
He's also concerned that business consultants might start using the underlying message of the book to convince clients that every good outcome is the sole result of positive thinking.
"They skew cause and effect to work in their favor, so that clients start believing they have all the answers," Dao says. In other words, good results are used as proof that it's working; negative results mean you're not doing right.
That's dangerous, he says, because it reinforces an urge to remain positive, even in the face of constant failure.
"People want answers and that's what The Secret and positive thinking gives them. But if your desire to have answers is greater than your desire for the truth, you're going to make some really bad decisions," Dao says.