Google Ngram's results for "propaganda". The term seems to have been most popular in a period that went from the 1940 to the 1970s, gradually losing interest in the following years. Of course, however, propaganda didn't disappear - it just went undercover.
I distinctly remember one day when I was - maybe - twelve; when my father saw me reading something that was lavishly illustrated with red flags and with hammers and sickles. He looked at that, very worried, then he relaxed. "Oh..., " he said, "that's fine: it is our propaganda." At that time, in the 1960s, my father was active in politics and the house was full of pamphlets of the Christian Democratic party.
Of course, also the other side, that of the communists, was using the same kind of naive propaganda methods and neither side seemed to think there was something wrong with that. My father, for instance, found natural and legitimate that his political side would openly engage in propaganda. It was "our" propaganda, fighting for us in the political struggle, just as "our" artillery was fighting for us in war. In a war, nobody would claim that the guns on their side were shooting flowers at the enemy.
It was only in later times that propaganda changed its face. The term never disappeared from usage, but it slowly fell out of fashion, at least in the sense that it became politically incorrect to say that one's faction was using propaganda. It was only something used by "them," not by us. "Our" side would never debase itself by using propaganda.
In part, the term "propaganda" was replaced by more neutral terms, such as "consensus building" and "public relations." In large part, however, in the West, propaganda went undercover; fully exploiting Baudelaire's observation that "the finest trick of the devil is to persuade you that he does not exist." It became refined, unobtrusive, subtle. And it was incredibly successful in convincing Westerners that it didn't exist - maybe for a while it even disappeared for real! Perhaps it wasn't needed any more during the period of Fukuyama's "End of History," when everybody got genuinely convinced that the collapse of the "evil empire", the Soviet Union, had shown the superiority of economic liberism. At that time, everyone knew that we just needed to sit down and relax to enjoy the goods that free markets would bring to us. There was no need any more to be told over and over that our enemies were dangerous, baby-eating monsters.
But, in recent times, something has changed. Propaganda is back with a vengeance. Here is just an example:
You see? No matter how you see the recent crisis in Ukraine, you have to admit that, in terms of propaganda, we are back to the methods of the 1950s and the 1960s, just a bit more sophisticated in graphical terms, but still based on the same simple theme: our enemies are baby-killing evil monsters. It is an accusation that has been fashionable and effective from the times when the Romans accused their Cartaginese enemies to sacrifice children to their god, Baal. Note how, in the image, they have managed to put the image of a child close to the title, "Putin's killed my son," even though they are completely unrelated stories (that shows, incidentally, the contempt they feel for their readers.)
We are not yet arrived to accusing Vladimir Putin of eating babies, but - as things stand - we may not be far away from that. Look at the image, here, titled "Bloodymir;" where Putin is shown with blood on his mouth, as if he had just finished his breakfast of child meat. And these are just a few examples of the new wave of propaganda that is invading the Western media. It is amazing how these simple tricks worked in the 1950s and 1960s and still seem to work today. And it seems that they are being used to take us straight to a new war. A lot of people, indeed, seem to be reasoning today just in the same way people reasoned in the 1950s: it is "our" propaganda, hence it must be good.
We can see propaganda as one of the several failed technologies of the 20th century, just like nuclear powered cars and weekend trips to the Moon for the whole family. Propaganda never promised to take us to the Moon, but, at the beginning it, was touted as a way to build informed consensus in a democratic society. That was the theme, at least, of Edward Bernays' 1928 book, titled "Propaganda," where he stated that that propaganda is not just good, but essential for democracy: "The conscious and intelligent manipulation of the organized habits and opinions of the masses is an important element in democratic society."
Evidently, something went wrong with these ideas. In its commercial version, propaganda became an instrument to convince us to buy things we don't need, while, as a political tool, it turned itself into the evil form we call today "psyops," the deliberate dissemination of lies to cast an enemy in a bad light. It is a form of black magic; powerful but extremely limited and often backfiring. Psyops can only create enemies, not friends. In the end, the effect is the opposite of what it was supposed to do in Bernay's times: by casting an external or internal opponent as "evil", consensus is destroyed, not created.
Nevertheless, Bernays had a good point: we need consensus. Of course, we don't need the forced uniformity that can be achieved by a dictatorship, but, without consensus on some basic points, it would not be possible to keep a democratic society going. The rule of the law, the need of due process, people's basic rights, are all part of this consensus. And there never was a moment as today in which we are so badly in need of consensus on such vital subjects as climate change and resource depletion which threaten the very existence of human civilization. But we are not achieving a significant consensus on these critical issues; what passes for "debate," today, is a sterile clash of absolutes were psyops have been used with great effect to destroy the credibility of a whole generation of climate scientists.
So, we are stuck: we need to manage a planet, but we don't know how to do it. Will we ever be able to find an agreement on something important that doesn't involve hating or bombing someone? Maybe there are ways, but we haven't found them, yet.
(*) Maybe you are curious to know what was the effect of a massive exposure to right-wing propaganda on a teenager (me) in the 1960s. Well, it is a long story, but I can tell you that too many and too blatant lies can badly backfire. The story of my very wavering juvenile political positions is not so interesting, but I can say that one of the reasons that led me to become a scientist was to search for an unbiased truth, somewhere, perhaps the result of the overexposure to propaganda I experienced in my youth. Over the years, I found that even science is not without biases, but, at least, in scientific debates we don't accuse our colleagues of eating babies.