Because you never know who you are talking to. You want people to think the best of you. Say you are accused of pushing a kid at recess. You have never lied to your teacher (your teacher knows this) and so they ask you, "did you push Billy" You reply with "No" she is more likely to believe you because you were honest an left a good impression. Another reason why its good to have a good impression is if you are being interviewed for a job. You want the employer to like you and want to hire you, so you should always put your best foot forward.
Thomas Paine questioned British authority for many reasons. Some of the main ones were that Britain is too far away and because of that should leave America alone; another was that they always wage wars in which America suffers; another was that the American people ran away from the crown just to be greeted by a country where the same crown rules. The list of reasons goes on and on and on.
Answer: keep your peace
Explanation: or keep one's peace. phrase. If you hold or keep your peace, you do not speak, even though there is something you want or ought to say.