An unethical method of achieving consensus on controversial topics. Propaganda thus differs fundamentally from scientific analysis. The scientist, on the other hand, is always prepared for and wants the most careful scrutiny and criticism of his facts and ideas. Science flourishes on criticism. Dangerous propaganda crumbles before it.
Authority implies an entitlement to credibility while expertise implies credibility has been earned.
To confidently proclaim a causal relationship one must rule out coincidences and ostensible causes with experiments designed to rule these out.