Friedrich Engels is the name of a philosopher who uses mathematical ideas to support the dialectic method he calls progress to perfection, which mathematicians however consider degenerate. Engels believes the tenets of Hegel's "Philosophy of Nature" but other natural scientists claim dialectic is incompatible with science. Engels works for eight years to develop a dialectic theory of nature that he admits fails and is unfinished. Despite his efforts, dialectical materialism is not developed as a constituted doctrine. Engels "negation of the negation" is impractical in a class struggle that sets capitalism as a positive term against the proletariat as a negative term, which thereby implies negative and positive in the same definition.