Unsignalled Information

Unsignalled Information

The message m communicated when a sentence S is broadcast regularly incorporates UNSIGNALLED information, information which – although not consulted in the generation of S – is nevertheless communicated by its broadcast.  To help fix the idea, here is a dramatic example: time-order in conditionals.

Conditionals are very often found to depict a fixed order of events, the if-clause’s first.  Thus the reason

If she misses the last bus tonight, Her Majesty will walk home beforehand

conveys nothing coherent is evidently that the final adverb essays a temporal relationship at odds with other temporal information ingredient in the natural interpretation of the sentence, specifically the temporal order of the satisfaction of the if-clause and the satisfaction of the main clause. Similarly, under the natural interpretations of these two

If she missed the last bus tomorow, she would walk home
If she had missed the last bus on Friday she would have walked home

satisfaction of the if-condition is very definitely understood as prior.  But that order of events is by no means mandatory.  Other conditionals include no such understanding, perhaps even the opposite one:

If Grannie escapes, it will be through the sewer
If they had collided, it would have been because Grannie was flying too low
If the Hun had attacked, we would have been ready for him
If this switch were on at present, the entire quad would be ablaze with fairy lights
If Grannie commits suicide, she will arrange it to look like murder.

Clearly, some conditionals incorporate interclausal temporal intelligence which others do not.  But notice, code-breakers, that there is nothing in any of these sentences to herald that information.  The encoding routine makes no provision for registering it.  The encoding routine can be relied upon to contrive the specification, however complicated, of an if-condition and a predication condition, it registers the location of a change-over point, and much else besides.  But it patently does not consult the question of time order at any point in the machine run. 

Time order could, of course,  be elicited by a more complicated encoding routine, one which makes available a slot for an appropriate adverb like ‘beforehand’ or ‘afterward’.  But then it would be outputting a different sentence.

Of course the hearer reads in the temporal information.  We can all appreciate that.  Indeed, it may have come as a surprise to you to work out that temporal order is nowhere encoded in any of these examples, so naturally did you read in the obvious order.  So should that order then be reckoned as part of the message? 

Our answer is: definitely.  With communication modelled as identity of message between minds, what is communicated surely belongs to the message; and this temporal information surely qualifies as communicated.  The hearer reads it in, certainly, but she (almost always) correctly reads it in.  She duplicates the very order of events the speaker has in mind, and the information, initially in one mind, is found subsequently in the other.

Time-order in conditionals is a dramatic example of unsignalled information, but the phenomenon is ubiquitous, and we shall make much use of the notion.  It is yet one more of those phenomena that can be expected, given that speakers and hearers of English have a modicum of knowledge and intelligence.  If they can be relied upon to regularly and systematically read in appropriate information in the course of making sense of a signal, what would be the point of encumbering encoding routines with extra machinery?  And what would be the evolutionary pressure to thus encumber?

Philosophers and Logicians (in particular) might care to examine in detail another standard example, the unsignalled information surrounding our use of English ‘and’.  Try this link, and then click on ‘And’ in the navigation bar.