According to Kurt Gödel, Bertrand Russell misinterpreted the incompleteness theorem, but did it in ʻa very interesting manner’. To understand what he meant we need to consider their attitudes to defining truth. Even more revealing is the discussion of two fundamental approaches to logic: one is universalistic, and assumed by both Russell and Gödel, and the other is model‑theoretical, Alfred Tarski’s style. It turns out that a misleading or erroneous interpretation can be interesting, as it reveals something fundamental. William Byers claims that truly great ideas in mathematics and about mathematics are in a way false, as they lead to errors, but at the same time they can help to make advances in math. Logicism provides a good example. In addition it may be mentioned that when Russell argued in its favor, he committed a logical fallacy.