At a recent conference, a colleague kindly pointed out that my interpretation of Spinoza had changed over the last two weeks, since I gave two rather different answers to the same question. Of course, it’s possible that I change or even improve my interpretation in the course of two weeks, but the suggestion was not really that I had improved my position. Rather, the assumption seemed to be that my utterances were inconsistent. Although we could settle the matter most amicably, such a situation can be quite a nightmare. Am I talking nonsense? Am I inconsistent without noticing it? Am I just opportunistically changing my views to align with certain people in the audience? Of course, I could also blame the listener: Was he being uncharitable? This matter is difficult to figure out. But rather than trying to figure out who is to blame, it might be better to ask what it is that affords (criteria for) consistency in the first place.

Let’s first look how important this is. It’s a common and rational expectation that authors be consistent. (This is why I include the following musings in my series on how to read.) If you read someone asserting that p and then asserting not-p, you can easily recognise their inconsistency by the very form of words. Of course, most types of inconsistency are a bit harder to detect, but once you notice them, you seem be faced with a choice: Either you find a factor that explains the inconsistency (away) or you have to doubt the rationality of the person whose text you read. Factors to deal with apparent inconsistencies are abundant features in interpretations. Faced for instance with Wittgenstein’s earlier and later philosophy, many readers think that he changed his mind or that he shifted his focus. A sensible and charitable reading of such changes will harmonise inconsistencies and look for evidence that confirms the assumption of a change of mind or focus. Even if it’s tricky to settle on a clear story of the changes in Wittgenstein, his case is fairly straightforward because he explicitly declares that he found his earlier work problematic. It’s harder, though, if no such evidence can be found. Of course, one might still assume that there is an explanation that resolves the inconsistency, but if no evidence can be found, we must also allow for the assumption that an author is in fact inconsistent.

But what does such a verdict amount to? I think we’re faced with a choice again: Either we assume a failure of what we call rationality, or we consider the option that consistency is too high a bar. What if authors are, by and large, more inconsistent than we like to admit? I think there is an explanation that leaves the rationality of the author untouched and focuses on what affords consistency. In philosophy, such factors might be found most straightforwardly in the debates that the author’s text is related to. What looks like a failure of rationality might in fact boil down to a change of debate. For me, some of the most obvious examples are to be found in medieval commentaries. Reading Ockham, I often thought he was inconsistent because he addressed problems for his position in one text, while he seemed completely oblivious to these problems in the next text. After a while, however, it dawned on me that the contexts and stakes were different. One text was a commentary on Aristotle’s logic; the other text was a mainly theological commentary on the Sentences of Peter the Lombard. Having noticed this changed my expectations as a reader across the board. While we might expect an author today to be consistent or “systematic” across their works, this might not have been a common expectation in other times or contexts.

Noting changes in genre or shifts in contexts is certainly good advice for texts of the past. But what about our own practices? Is consistency really a feature of what we call rationality? Or might the phenomenon by much more “local”, pertaining more to certain stable contexts such as debates rather than to minds? For the time being, I’d like to settle for the assumption that consistency is a feature of debates rather than authors.