Silence is not "a tool of criticism", especially in a forum or assembly of people. It is a tool of assent Ok, I'm going to disagree with this--or at least put in a disclaimer. Speaking from personal experience, silence can also be the result of a decision that not saying something is better in a particular circumstance than saying something. It is a matter of priorities, and degrees--and I think we each set those for ourselves. I doubt that there is a single reader here (who has read more than just a handful of posts) who has not disagreed with something said. And I for one am very thankful that we have refrained from posting every little disagreement; if that were the case, I imagine that's about all we'd be reading. It, um, may have been rather obvious, of late, that I bristle right up when in my opinion my friends are attacked. At the other end of the spectrum, for ex., when various people disagree over whether a word came from Greek or Latin, I mentally yawn and move on: I have no vested interest in such a thing. And I feel sure that everybody has such things. Yet, even where I do have a vested interest, there are many reasons--for manners' sake, being one--that I refrain from voicing my disagreement. As to degrees: I believe we each have our "threshold" at which we will tolerate no more, and that this varies from person to person.
Edit: hmm, I was giving some thought to why I broke my silence and made this post. It is because I tend not to like generalisms, and particularly dislike having them applied to me. I have discovered, comparatively recently, that my anger is quickly aroused when someone presumes they know my entire motivation. Trust me: you (you, as in the world, not you in particular, moss) don't, unless I have specifically told you. It also makes me angry when I have laid out my entire motive with complete honesty, and someone still says, "Yeah, but what's your real agenda?"
E. Edit (like P.P.S., ya know): DubDub--you did a much better job than I!