Steve Keen argues that if you assume the labor theory of value is wrong, then this obviates the bulk of the critique. Keen suggests that the TRPF was based on the idea that only labor can create new value (following the labor theory of value), and that there was a tendency over time for ratio of capital to labor (in value terms) to rise. However, if surplus can be produced by all production inputs, then he believes there is no reason why an increase in the ratio of capital to labor inputs should cause the overall rate of surplus to decline.