The goals of the Piltdown Man hoax revolved heavily around nationalistic ideals. The Piltdown Man was a way for England to join in on Europe’s archaeological finds but finding something older and “better.” The push to put England on the archaeological map worked, too, because it was popular through both the scientific and the public spheres. Not only was it accepted because of the desire for England to have a find of it’s own, but the idea of the Piltdown Man, a man who could showcase the brain centered perspective of human evolution, coincided with the current scientific paradigm. Of course on a personal level for Dawson, there was the idea of fame as an archaeologist. The Piltdown Man was even named after him, Eoanthropus Dawsoni.
The Cardiff Giant on the other hand was a scheme born almost entirely out of greed. Hull, one of the perpetrators of the hoax and a strong atheist, claimed it was to prove that people would believe just about anything; however, he didn’t speak up about the hoax once people started believing it so it was clearly about money as well. Truthfully, he may have been right as the public believed without question, even if the Cardiff Giant clearly looked like a sculpture (though maybe a majority of the people who saw him hadn’t seen fossils before so it wasn’t as obvious to them? Still though, one person even said the chisel marks were visible.) With the Cardiff Giant people wanted to believe because it was in the bible, it proved that there were giants in existence, not that it was just a fable or some exaggerated tale.
The Cardiff Giant encouraged biblical literalism, and in turn perhaps encourage young earth creationist ideas. It was definitely anti-evolution. Though it never fooled any actual scientists, it’s clear that the public’s opinion holds serious water in the way society functions. People who are anti-evolution can protest teaching evolution in schools, and in some places succeed, which prevents education of newer generations. As a (self-proclaimed) democracy, the people and how they are educated makes a big difference in what laws are made, and what things a society can accomplish.
The Piltdown Man had a similar hand in miseducation, but this one included authorities in the scientific communities. This is incredibly dangerous because not only did it continue the spread of misinformation, when it came to light that it was a fake it weakened the trust between the scientific community and the public, and it created space for religious zealots to point fingers and claim scientist are liars or idiots. This rift between public perception of scientists and the truth is a lasting one, with people still pointing at the Piltdown Man as a sign that science can’t always be trusted.
I think these hoaxes show the self-corrective nature of science. Scientists themselves weren’t the ones fooled, and despite the damage they may have done in the public sphere peer-review of these “discoveries” showed over and over that they were hoaxes.