Comments on an article by Kristof Kovacs and Andrew R. A. Conway (See record 2016-38353-001). Process overlap theory (Kovacs & Conway) provides an interesting account of basic elements of some mental processes—especially those that include working memory tasks and abstract reasoning tests (such as Raven’s Progressive Matrices). The theory appears to be internally consistent within the boundaries that are described in Kristof Kovacs and Andrew R. A. Conway’s target article. Yet there is something highly unsatisfactory when the theory is presented as accounting for general fluid intelligence (Gf), a general factor of intelligence or even general intelligence, as represented in the article. Kovacs and Conway describe a variety of theories of the structure of intelligence and provide a good review of one approach to intelligence. But the approach is almost entirely devoid of any consideration of the much larger field of intelligence research and application. There are some additional concerns about the approach proposed by Kovacs and Conway. Correlation and causation. There are two things to say about this issue. First, “accounting for” variance via correlations can be informative, but correlations, in and of themselves, do not provide proof of causal relations.