We are told as children that it is polite to be pleasant and say Yes. Even if we aren’t told, we find quickly that it is much more rewarding to smile and say Yes. Other people want us to agree, comply or fall in line. Perhaps they like being told, in effect, that they are right. They love to hear others echo their point of view. Even if they are smart and guess you don’t wholeheartedly agree with them, they still like your endorsement. Your stock goes higher. They just want to hear that Yes.
We also find that many think that to disagree is to be disagreeable. You may give very good reasons when you say No, but it rarely helps. Your friends, colleagues and acquaintances think you dim-witted or pig-headed. If you are unlucky, they also think you perverse. Your No seems to them a badge of dogged unreasonableness.

Yet, a Yes is not without its price. The biggest problem is that, once you say Yes, it is hard to switch later to a No. Once you agree to babysit somebody’s kid, you will be called upon to babysit on all future occasions, whether there is a real emergency or they just want to see the next Batman movie. Once you nod sagely as your boss talks ecstatically about free trade, you will spoil your relationship if you ever make the slightest protectionist noise. Nobody is interested in the subtlety of your reasoning. The slightest suspicion that you are about to change your tune will bring down on your head the wrath of the spurned.
You might as well cry in the desert than expect your friends to remember Emerson’s dictum about consistency being the hobgoblin of little minds. Nobody cares how much you have studied of late, how your views have evolved, you will be scorned as a turncoat with no sense of loyalty or a weather-cock with no inkling of ideology. You may have genuinely come across new facts or parsed your way to different ideas, but your switch from Yes to No will attract the worst of interpretations.

The other reaction is to equate pleasantness with gullibility. A woman, I am told, who tries to be sunny and gracious with a car mechanic is liable to be seen as a ‘softie’ and a prime target for overbilling. A new female entrant to an office dominated by males, who tries to be friendly and helpful, may quickly find herself loaded with unwelcome chores and taken advantage of in less savory ways. If she then tries to change her ways and act less obliging, a virulent response is to characterize her as stiff and standoffish. Even other female employees may offer unkind evaluations of the new person as too coquettish or too haughty.

The first condition for being able to say Yes to something I believe worthwhile is to be able to say No to something I no longer care for.