The most important thing.....second-level thinking

Okay, so I just started reading The most important thing, and I've finished the first chapter. Here's what I learned in chapter 1:

In the first chapter, Howard Marks stresses the importance of second level thinking. What is second level thinking? Second level thinking-from what I have understood-is the process of analysing all the opinions, the possible outcomes, and the probability of these outcomes. This is because, in order to be a successful investor, you have to regularly outsmart a generally efficient market. To achieve that, you have to hold an opinion different to that of the consensus, and be certain of its probability. He gives the example that a first level thinker might say, "its a good company-buy", whereas a second level thinker might say "its a good company, but everybody thinks its a great company-sell".