Francesco Fiorentino's book Gregorio da Rimini: Contingenza, futuro e scienza nel pensiero tardo-medievale (2004) is riddled with errors. For example, here is n. 16 on p. 9 of the introduction:
‘C. Normore, Peter Aureoli and his contemporaries on future contingents and the excluded middle, "Synthèse", 96 (1993), pp. 83-92. Nel 1999 C. Normore è ritornato sul tema secondo una prospettiva più ampia; cf. C. Normore, Contingenti futuri, in La logica nel Medioevo, The Cambridge History of Later Medieval Philosophy, a cura di N. Kretzmann, A. Kenny, J. Pinborg, Milano 1999.’
An attentive reader working on future contingents will immediately spot three mistakes in this one footnote. The first two are comparatively insignificant: the title of Normore's article begins with ‘Petrus’ and does not contain the definite article. The third is more worrying: the CHLMP was published in 1982, so Normore's 1993 article appeared after his CHLMP chapter, but Fiorentino (presumably using a 1999 translation) tells us that in the latter Normore ‘returned to the theme from a wider perspective’. The worrying thing is that the CHLMP has been the standard handbook of mediaeval philosophy since its appearance over 25 years ago.
Both author and publisher deserve a rap on the knuckles, so I was pleased to discover that Mark Henninger had already reviewed the book in Gregorianum. Pleased, that is, until I read the review.
Henninger is grateful for ‘certain logical principles he wisely provides in the introduction [actually Chapter 1]: the principle of bivalence, i.e., in whatever statement, either its affirmation or its negation is true; the law of contradictories, i.e., for every affirmative statement there exists its contradictory, and vice versa’. Unfortunately, both of these are more or less obvious howlers on Fiorentino's part.
If the meaning of ‘bivalence’ in a logical context is not clear enough from the etymology, even a standard dictionary will define it as the existence of only two truth-values, the corresponding principle being that every statement is either true or false. Worse, Fiorentino goes on (p. 24 n. 23) to cite Łukasiewicz's insistence on distinguishing between the principle of bivalence and the law of excluded middle. A reader following this up will be astonished, given Fiorentino's formulation, to read on p. 82 of Łukasiewicz, Aristotle's Syllogistic: ‘…the so-called principle of bivalence, which states that every proposition is either true or false, i.e. that it has one and only one of two possible truth-values: truth and falsity. This principle must not be mixed up with the law of the excluded middle, according to which of two contradictory propositions one must be true.’
As for the law of contradictories, Fiorentino refers only to Aristotle, De int. 9, 18a28-31. The reader following this up will find a discussion of the truth or falsity of an affirmation and its corresponding negation – not the mere assertion that there is a corresponding negation. And I think the reader checking in Rimini and Auriol will find that the law of contradictories is that if one part of a contradictory pair is false then the other part is true (Rimini), or vice versa (Auriol).
Henninger's verdict is that ‘Fiorentino provides a well-researched, thorough and balanced investigation of the teaching of Gregory of Rimini … In the introduction, Fiorentino sets the context with a helpful historiography of the problem of future contingents and divine foreknowledge as treated mostly by researchers in the last century, as well as a survey of the literature on Gregory of Rimini. … This is a fine work by a fine scholar.’
Sadly, then, Fiorentino's book still awaits a properly critical review.