Ralph is taking a stand, and taking responsibility. Jack and his group are not the only ones at fault, and Ralph finally acknowledges this fact.
Ralph clung to his ideas of organization and order, and at times risked life and limb to fight about them. Jack and Ralph were engaged in a power struggle-and both had a hand in the way things went wrong. Ralph would engage in violence to make a point, when Jack would goad him into it. All the boys were to blame for their descent into savagery. Ralph had until this point, refused to see that he too, had a savage side.