Before Darwin could convince his readers of evolution through natural selection, he had to acknowledge the reasons that people did not agree with evolution through natural selection. On page 482, Darwin says “nothing had first can appear more difficult to believe than that the more complex organs and instincts should have been perfected, not by means superior to, though analogous with, human reason, but by the accumulation of innumerable slight variations, each good for the individual possessor.” Darwin admits that the idea is hard to wrap your head around, especially for the time. Darwin then says that we cannot dispute the fact that all organs and instincts are variable, that there is a struggle for existence leading to the preservation of each profitable deviation of structure or instinct, and that gradations in the perfection of any organ or instinct exist or could have existed, each good of its kind. (Pg. 482) Ultimately Darwin talks about infertility of hybrids, imperfections in our geological record, and the geological distribution of the species. He talks about how those are gaps in the theory of evolution for natural selection, and then he explains to the readers why they happen. He takes us through a chain of events that ultimately show us that there is variation in nature, causing different groups to form a different species. He also talks about how there is competition in nature because of the struggle for survival.
One of the arguments I found interesting was the argument about chains of descent. Scientists at the time did not believe in chains of descent and Darwin came along and argued that all species come from a long line of descent. I think the most convincing thing he talked about was just the fact that humans have come from a chain of descent and they have evolved over time. Although it probably seemed weird for the time, Darwin still pursued the idea that humans are involved in an evolutionary process. We now learn about the evolutionary process in class, which makes it even more convincing.