  [F]ormal logic and general philosophy have more to bring to one another than is sometimes supposed. I do not mean by saying this to underrate the work of those who have explored the properties of symbolic calculi without any concern as to what they might be used to mean … Nor do I mean to underrate what recent philosophers have done in the way of exploring the obstinate and intricate ‘logic’ embedded in common discourse, even when they have not derived or sought to derive anything like a calculus from it … But these activities are, or can be, related to one another very much as theory and observation are in the physical sciences; and I must confess to a hankering after well-constructed theories which much contemporary philosophy fails to satisfy. (1957: vii.)