Darwin's theory was accepted long before crick and watson showed the d. Natural selection is not a mechanism, it's description. Even mor classic example of this is newton's gravity which is just an equation. So we only want to make the realist claim that the world is actually different when we have a mechanism. And sometimes that matters, and sometimes it doesn't.
Everyone has heard of the term “pseudoscience”, typically used to describe something that looks like science, but is somehow false, misleading, or unproven. Many would be able to agree on a list of things that fall under its umbrella — astrology, phrenology, UFOlogy, creationism, and eugenics might come to mind. But defining what makes these fields “pseudo” is a far more complex issue. Given the virulence of contemporary disputes over the denial of climate change and anti-vaccination movements — both of which display allegations of “pseudoscience” on all sides — there is a clear need to better understand issues of scientific demarcation. Shermer and Gordin explore the philosophical and historical attempts to address this problem of demarcation.