Growing up, most of us were taught to “think before we speak”. That’s basically what a filter does. It prevents you from saying something that you may regret later and it allows you to speak confidently after having mulled over it a while.
Having a filter prevents embarrassment. Having a filter prevents you from losing your job over saying something silly. And for people in authoritative positions, having a filter prevents serious economic damage at the minimum.
President Trump does not have a filter. He has already alienated one of their largest trading partners, Mexico, over talks about making Mexico pay for the wall. He has no sense of when it is appropriate to talk about certain topics, like when he was discussing about the inauguration crowd size in front of a memorial to CIA officers who died on duty.
Before he causes any more damage and embarrassment both to himself and the United States, he needs to grow up. Someone needs to advise him, both on his verbal speeches and on his Twitter, on how to act more Presidential. It’s about time he acts like any normal President would.