Why is it so hard to give AI common sense?

• Computers have mastered many games involving strategy and logic(like GO and Chess), but common sense learning is a dream.
• AI(artificial intelligence) may be great at algorithmic computations but falls flat when tackling real-world complexities.
• Modern AI can handle specific problems, but common sense is hard to master as it is vague and does not come with a predefined set of rules.

Machine learning of common sense is now considered a moonshot problem, requiring intensive collaborative efforts from different institutions and organizations. 

Understanding natural language and answering simple questions are the first steps towards building common sense in machines.

To learn common sense, machines would have to master sociology, psychology, planning and execution, emotions, threat detection, background knowledge, and many abstract concepts.