 Russell’s theory of descriptions was introduced in his paper “On Denoting” (Russell 1905) published in the journal Mind. Russell’s theory provides the logical form of sentences of the form ‘The \(F\) is \(G\)’ where ‘The \(F\)’ is called a definite description in contrast with ‘An F’ which is an indefinite description. The analysis proposes that ‘The \(F\) is \(G\)’ is equivalent to ‘There is one and only one \(F\) and it is \(G\)’. Given this account, the logical properties of descriptions can be deduced using just the logic of quantifiers and identity. Among the theorems in *14 of Principia Mathematica are those showing that, (1) if there is just one \(F\) then ‘The \(F\) is \(F\)’ is true, and if there is not, then ‘The \(F\) is \(G\)’ is always false and then, (2) if the \(F = \text{the } G\), and the \(F\) is \(H\), then the \(G\) is \(H\). These theorems show that proper (uniquely referring) descriptions behave like proper names, the “singular terms” of logic. Some of these results have been controversial —Strawson (1950) claimed that an utterance of ‘The present King of France is bald’ should be truth valueless since there is no present king of France, rather than “plainly” false, as Russell’s theory predicts. Russell’s reply to Strawson in (Russell 1959, 239–45) is helpful for understanding Russell’s philosophical methodology of which logical construction is just a part. It is, however, by assessing the logical consequences of a construction that it is to be judged, and so Strawson challenged Russell in an appropriate way. 