Calling public relations a science doesn't make it one.
Edward Bernays, who is often called the father of public relations, was the first to claim that public relations a science. In a 1935 essay titled "The Engineering of Consent," referred to public relations as "an applied social science" comparable to other applied sciences such as engineering and aeronautics. Then, and throughout his 70-year career as a very high-priced public relations practitioner, Bernays urged practitioners to make public relations work more precise, scientific, statistical, and predictable.
Some practitioners agreed with Bernays, but there were probably far more who didn't. But, at that point in public relations' development, they kept their mouths shut. Bernays was too well-known, respected, and powerful to publicly disagree with him. Consequently, there were few books or articles saying that public relations was not a science until the 1970s and later when authors like Lawrence Nolte, Marvin Olasky, and eventually Michael Levine began speaking up.
In his 1974 book, Fundamentals of Public Relations, Nolte wrote: "In one sense the public relations man is akin to the weatherman who says there is a 60% chance of rain. These odds are not at all unreasonable. They are not, however, reliable enough to put public relations in the same category with engineering or any of the hard sciences."
Levine who wrote almost 20 years later was even more pointed in his book, Guerrilla P.R. He wrote: "In science, two plus two equals four. It will always equal four whether added by a Republican from Iowa, a shaman from New Guinea, or an alien from Planet X. However, in public relations, two plus two may equal four. It may equal five. It may equal zero today and fifty tomorrow."
Sarcastic? -- Perhaps. -- But, there's a lot of validity to Levine's perspective. In a true science, just as in math, performing the same tasks in the same order produces the same results regardless of how many times you perform them. The outcome or answer doesn't change. That's not true in public relations. The outcome you achieve, when you precisely duplicate a set of previous actions, will not necessarily be the same as it was the first time. It could be, or it could be similar, or it could be dramatically different.
This isn't to say public relations doesn't use scientific and statistical techniques. It does. Lots of them. And, they get more numerous, more complex, and more accurate all the time. Public relations also uses computers and high-tech communication systems. In fact, most public relations activities are steadily becoming more technology-based, knowledge-dependent, and measurable. But, despite this, public relations practitioners still have to contend with the unscientific unpredictability and contrariness of human nature and free will. There simply are no guarantees or certainty in predicting public relations outcomes because there are no guarantees or certainty in predicting human behavior.
In some ways, this uncertainty is part of what makes public relations such a fascinating profession in which to work.