What theoretical approach is linked to the philosophical doctrine of materialism?

The answer is "the social-conflict approach".

The social conflict approach is a way to deal with social theory that contends that society is described by different disparities and clashes that reason individuals to act socially, delivering change.  

Society, according to the social conflict approach, isn't amicable. It's not steady. Society doesn't create agreeable balance. Truth be told, it's overflowing with imbalance. So this methodology is extremely about investigating imbalances of race, class, sexual orientation, and ethnicity, and the social clashes which result. Basically, these contentions will result in change, changes that will move society.

in this part of the declaration it refers to the point when american people didn't recognize the british domain and   breaks the political bands with britain, they forced a respectful separation.

mankind was created and entitled equally with rights   which were life, freedom and the seeking for happiness.