The solutions each of us proposes for problems of the world, if we took the time to think about it, depend very much on our intellectual and moral inclinations and starting assumptions.
I very much believe that there is a human nature which is innate to every human being that, at the crux, cannot be altered by socialization or some kind of mere hope, morality or ideology. This starting belief informs my intuitive interest in subjects like evolutionary psychology, Realism and Marxism, because such subjects are inspired by how so many aspects of our behaviour do not change despite the long span of human history. The patterns just inevitably keep repeating themselves, as evidenced by the vast literature of war, societal conflicts and love throughout the ages.
Despite numerous social movements that have seen humans living through the chastity of Victorian England, the oppression of Maoist China, the enlightenment of Renaissance Europe to the decadence of the Dark Ages (an obviously inexhaustive yet clearly diverse list), fundamental aspects of aggression, attraction, status hierarchies, coalition formation, kinship and reciprocity, just to name a few, still remain. Despite the promise of Liberalism and Idealism, which are all logically sound philosophies, wars still happen and states are still concerned with security. Exploitation still happens all over the world, at both global levels (the exploitation of third world nations by advanced capitalist states) and smaller levels (the exploitation of the poor by corporations).
I don't think I'm wrong in my judgment of the reality in this sense, even if it may appear rather bleak or, worse, nativist. It is clear that, with recurring travesties of war, discrimination, exploitation etc in the world today, the power of socialization (trumpeted by behaviourists, social constructivists and environmentalists amongst others who believe entirely in nurture/culture while refusing to acknowledge nature) and the power of cooperation (because man is good and rational) requires a serious raincheck. The worst thing to do, given where my intellectual concerns come from, is to deny that human nature exists and dictates a significant chunk of our motives and actions.
This is dangerous because denying our nature and our propensity for certain behaviours is to diagnose the problem wrongly and suggest the wrong cure. It is perhaps striking how so many people are surprised when others behave in a self-interested manner, or are upset in the sense that they get caught off guard when war and conflict happens. It reflects, perhaps, a certain kind of self-delusional belief that social theories of learning and positive reinforcement can eradicate 'bad' traits in humans. John B. Watson (1930), the founder of behaviourism, famously said, "Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors." Clifford Geertz, a firm believer of the culturally malleable human, also defined how many social scientists think today and therefore a large degree of the entire social sciences enterprise. Hence, to these theorists, "change society or culture and you change people... Intelligent, scientific socialization can make us whatever we want to be" (D. E. Brown, 1991).
The attempts to suppress 'bad' human nature have been huge fiascos. Suppression often results in a rebound effect, and large scale oppression of natural tendencies are bound to either fail (consider the Kibbutz movement, the Hippie movement or the feminist movement, just to name some) or will experience some 'leakage' - the secret societies that operate underneath a lawful society, the rich husband who cheats on his wife, the insecure friend who behaves competitively even though the friendship is tight. I guess with such high hopes for a better world, it should come as no surprise that many people are disappointed or jaded with the outcomes.
It should make more sense, then, to find ways to work with/around our human nature, instead of working against it. Monogamous marriage law is a great example to cite. If men are most aggressive when they have no mates, institutionalize monogamy. This solved the huge problem of a lack of females in society for men who weren't rich or powerful enough to get wives (although you get the problem of the cheating powerful husband because he is driven to seek extramarital affairs, but that's a small cost compared to the huge benefits of reduced societal violence). Realism provides the wisdom that states seek security, so find ways to induce balance of power. Zhuge Liang knew this so brilliantly when foresaw that stability will be achieved when the three kingdoms were balanced against each other. Marxism tells us that the rich elite will exploit the poor. So empower the poor - give them welfare and education - and offset the power differential between the bourgeosie and the proletariat. Stubbornly refusing to acknowledge exploitation, or perhaps worse, calling it by another name (comparative advantage and mutual gains?) to hide its dark side, will not result in betterment for society.
Betterment will come slowly, as it often does. With my basic starting assumptions outlined above, I believe the creation of institutions that work with human nature are often the solutions that succeed and result in progressive change. A good sense of creativity and level-headedness, with a healthy dose of reality, will go much further than overzealous revolution or radicalism with the refusal to acknowledge that our human nature cannot be denied and won't go away.