When I was a kid, I annoyed my teachers and a lot of other students by trying to answer every question that my class was asked. I don't know if I tried to answer every question because I knew the answers or because I wanted people to know how smart how I thought I was. Probably a little bit of both. In any event, people didn't really seem to care or notice how smart I was because they were so annoyed with me. One day, my teacher, very gently pulled me aside and told me that she knew I was very smart but that I needed to let the other students answer some questions, too.
From that day forward, I started waiting to answer questions until no one else could. When I held my tongue and waited, I discovered two interesting things. One, people still assumed I knew the answer and, two, waiting to raise my hand normally gave me enough time to figure out the answer when I didn't know it already. So, somehow, in my silence, people still thought I knew all the answers, even when I didn't. When I was answering every question, people knew when I didn't have the answer because I didn't jump to answer it. When I started holding my tongue, people assumed I had the right answer even when I was just as stumped as everybody else.
Proverbs 17:28 describes this phenomenon. "Even a fool is considered wise when he keeps silent, discerning when he seals his lips" (HCSB). Just like when I was a kid, there are times we get the urge to open our mouths and just start talking. We think we have to share our opinion with everyone who disagrees with us or correct everyone we hear state an incorrect fact. Sometimes, we want people to validate us so much that we try way too hard and always have something to say. But the reality is that knowing when to keep one's mouth closed is often a much greater sign of wisdom than having something to say. Especially because, sometimes, we just don't know what we are talking about.
I once heard a saying (I think from my mother, but don't hold me to that), "People may think you're dumb, but they don't know for sure until you open your mouth and confirm it." Sometimes, holding your tongue gives you the time you need to figure out the right thing to say. Sometimes, it gives you the extra time to discover that missing piece of information. Sometimes, holding your tongue frees you to discover that you don't really have to say anything at all.
When in doubt, hold your tongue. Even a fool is considered wise when he keeps silent.