This is a really interesting question. Let's break it down. Firstly, what do we mean by conservatism? We can broadly define it as a belief in traditional values and ideas, combined with a belief in private ownership and market liberalism (free markets). Secondly, by an ideology of human imperfection, I take it that you mean something along the lines of the idea that humans are not perfect and have many faults, and that our political ideas should take this into account when constructing a society. To some extent, an assumption of human imperfection does exist within the ideals of Conservatism. Free markets primarily see individuals as a rational, free agents who can and should make decisions for themselves. On a secondary level however, economics recognises humans as myopic - we make short term decisions that increase our utility. Conservatism takes it as true that humans are self-interested, and therefore our economic system should be designed to work around this. Additionally, traditional values often support policies such as a firm judiciary system that prioritises punishment over reform for criminals. Again, such a system assumes that humans are fundamentally flawed, and those who are unable to follow the rules should be punished. In both examples, there is an undercurrent in which human flaws should be worked around to create a better society. That being said; many political ideologies recognises human flaws - even socialism recognises that it's because humans can't be effectively trusted to share and allocate resources that the state should intervene and help those in need. In summary; there is a degree to which Conservatism requires an assumption of human imperfection, but this assumption is not limited to Conservatism, and there is disagreement as to whether or not this is an essential property of Conservative thought. For more, feel free to get in touch!