Wednesday, September 28, 2011

Unexpected but Predictable

The NonSequitur is a blog that investigates reasoning errors in the wild. This is admirable but tricky work -- apparent reasoning errors can turn on you suddenly if you don't watch out -- so I tend not to criticize even when I think their claims a little strained. But I cannot bear pointing out that this post is entirely wrong. The argument is that there is a contradiction, or at least a tension, to the following statement:
What Herman Cain did in Orlando this weekend was both completely unexpected and entirely predictable.
To this Scott Aikin replies that it can't be true. But of course it can: the situation in which something was predictable but unexpected is the situation in which it could have been predicted (and thus was predictable) but no one actually did predict it (and therefore it was unexpected). Since such things do happen, the original statement is entirely fine, logically speaking; any tension is the deliberate rhetorical tension that arises from foiling expectation. And it's clear from the rest of the paragraph in which this sentence is found that this was precisely the point: the idea is that nobody expected it, but given what it would take to win the straw poll, it was "in some sense inevitable".

I don't think this is a silly error, though, since you could very well read 'predictable' as saying that it was predicted (and thus expected). What it points to is that there is a whole class of ability-words and ability-phrases that are potentially ambiguous, being the sort that can be read either as indicating mere potential or as indicating activated potential. The best known and most widely used example is 'visible', which can mean either that something is see-able, or that something is seen (and thus see-able), but there are a number of others: sensible, intelligible, and so forth. Interesting, most of them are broadly cognitive in character, although you can occasionally find them in other contexts -- in the Aristotelian terminology of Aquinas's Third Way, for instance, the 'possible to be' and and 'possible not to be' is elsewhere shown to be precisely such a phrase, intended to be read in the activated-potential sense; it's a way of understanding the phrase we don't typically use anymore, which is why it takes some effort to read the Third Way in the sense it was intended to be read.


  1. Leo Carton Mollica8:51 PM

    Do you know of any articles that advance an interpretation of the tertia via along the lines you suggest?

  2. branemrys9:14 PM

    As I recall, there's an article by Lawrence Dewan in Dialogue from a few decades back that notes the connection with other discussions (and in particular in Aquinas's and St. Albert's commentaries on the De Caelo) that make the meaning of the phrase more clear. I'd have to dig up the precise reference, though.

    Aquinas addresses the issue in the (somewhat involved and difficult) section of the De Caelo commentary concerned with these issues -- Book I, lectures 24-29 (sections 237-285; see esp. 253-256). Basically the idea is that things are possible-to-be or possible-not-to-be (or necessarily, or impossibly) in the relevant sense for specific times; and since everything exists for as long as it is able, nothing begins to be before it can be and nothing ceases to be until it can't be.

  3. branemrys9:25 PM

    I should add that the way I've put it in the post is potentially confusing. Things are possible-to-be and possible-not-to-be for determinate periods of times; things can be possible-to-be and possible-not-to-be at the same time, but not for the same period of time. The ability-sense is an activated potential sense when this time interval is included: things that are possible-to-be for a period of time, actually are; things that are possible-not-to-be for a period of time, actually aren't. If an object is able to be for three minutes after noon, it actually does (or will, or did) for those three minutes and if it is not able to be at any other time, it actually does not exist (or will not, or did not) for those times.

  4. Michael Sullivan10:13 PM

    "reasoning errors in the wild" - that's great.


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