The amount of knowledge that exists is infinite and thus one can only truly know everything by merging with the infinite, God. Any state of being that is less than this state of being is a state of being where intelligence is limited. The degree to which you are disconnected from the infinite, as is indicated by the way you feel, is the degree to which you are intelligent.
Since the majority of all living people are severely disconnected from the infinite, stupidity is often encountered by those who are living and interacting with others. In fact, stupidity is the sole cause of suffering and conflict in the Universe, because as people disconnect from the infinite, they attract experiences that match as they lose sight of the truth of the Universe and thus choose poorly as they select topics to focus upon. If you ever find yourself wondering why an unwanted situation is unfolding, you can always pinpoint the cause as being that of stupidity, a disconnection from the infinite.
To combat stupidity, you can begin to make wiser choices by choosing to focus on the best feeling points of focus you can find and thus increase your intelligence as you gain access to more information by merging with and gaining more access to the infinite. This process will result in your developing of more intelligent thoughts using a better decision making paradigm that is capable of generating more intelligent ideas, solutions, plans, etc. and you will essentially be and feel smarter just by tapping into a vibrational frequency that is closer to the infinite vibrational frequency.
In other words, by allowing more of the energy that is the infinite, you will be and feel smarter as a result. It can also be said that you are at your most intelligent when you are giving your attention to the best feeling point of focus you can find. When you are giving your attention to the best feeling point of focus you can find, you are allowing more of the infinite energy to flow through you and thus have greater access to the infinite amount of knowledge in existence due to your allowing of the infinite. Thus, you are at your most intelligent when you feel the best you can possibly feel and you are also in the closest possible proximity to the infinite as well.