Samuel Langhorne Clemens, a novelist popularly known with his pen name Mark Twain (1835-1910), sees public opinion to be mostly social signaling or about attaining social conformity or "corn-pone opinions", rather than independent thinking.
A longish excerpt from Mr. Twain (at the LewRockwell.com) [bold mine]
Our table manners, and company manners, and street manners change from time to time, but the changes are not reasoned out; we merely notice and conform. We are creatures of outside influences; as a rule we do not think, we only imitate. We cannot invent standards that will stick; what we mistake for standards are only fashions, and perishable. We may continue to admire them, but we drop the use of them. We notice this in literature. Shakespeare is a standard, and fifty years ago we used to write tragedies which we couldn't tell from – from somebody else's; but we don't do it any more, now. Our prose standard, three quarters of a century ago, was ornate and diffuse; some authority or other changed it in the direction of compactness and simplicity, and conformity followed, without argument. The historical novel starts up suddenly, and sweeps the land. Everybody writes one, and the nation is glad. We had historical novels before; but nobody read them, and the rest of us conformed – without reasoning it out. We are conforming in the other way, now, because it is another case of everybody.The outside influences are always pouring in upon us, and we are always obeying their orders and accepting their verdicts. The Smiths like the new play; the Joneses go to see it, and they copy the Smith verdict. Morals, religions, politics, get their following from surrounding influences and atmospheres, almost entirely; not from study, not from thinking. A man must and will have his own approval first of all, in each and every moment and circumstance of his life – even if he must repent of a self-approved act the moment after its commission, in order to get his self-approval again: but, speaking in general terms, a man's self-approval in the large concerns of life has its source in the approval of the peoples about him, and not in a searching personal examination of the matter. Mohammedans are Mohammedans because they are born and reared among that sect, not because they have thought it out and can furnish sound reasons for being Mohammedans; we know why Catholics are Catholics; why Presbyterians are Presbyterians; why Baptists are Baptists; why Mormons are Mormons; why thieves are thieves; why monarchists are monarchists; why Republicans are Republicans and Democrats, Democrats. We know it is a matter of association and sympathy, not reasoning and examination; that hardly a man in the world has an opinion upon morals, politics, or religion which he got otherwise than through his associations and sympathies. Broadly speaking, there are none but corn-pone opinions. And broadly speaking, corn-pone stands for self-approval. Self-approval is acquired mainly from the approval of other people. The result is conformity. Sometimes conformity has a sordid business interest – the bread-and-butter interest – but not in most cases, I think. I think that in the majority of cases it is unconscious and not calculated; that it is born of the human being's natural yearning to stand well with his fellows and have their inspiring approval and praise – a yearning which is commonly so strong and so insistent that it cannot be effectually resisted, and must have its way.
Read the rest here
Bottom line: Without independent-critical thinking, we become subject to the mind manipulation-control ruse or easily succumb to indoctrination (brainwashing) schemes employed by various vested interest groups via populism. Think collectivism, statism, nationalism, demand based economic policies, climate change, and more...