Sympathetic to both business and labor, Roosevelt avoided labor strife, most notably negotiating a settlement to the great Coal Strike of 1902. He dramatically expanded the system of national parks and national forests. After 1906, he moved to the left, attacking big business, proposing a welfare state, and supporting labor unions. Roosevelt appointed three associate justices of the Supreme Court. First, progressivism promoted use of science, engineering, technology, and social sciences to address the nation's problems, and identify ways to eliminate waste and inefficiency and promote modernization. Those promoting progressivism also campaigned against corruption among political machines, labor unions, and trusts of new, large corporations, which emerged at the turn of the century. In describing Roosevelt's priorities and characteristics as president, historian G. Warren Chessman noted Roosevelt's insistence upon the public responsibility of large corporations; publicity as a first remedy for trusts; regulation of railroad rates; mediation of the conflict of capital and labor; conservation of natural resources; and protection of the less fortunate members of society.