But what counts as a stupid question?
1. Some say there are no stupid questions, only stupid answers. When Bill Gates asks "What is a network?", this could either be interpreted to mean that Bill Gates is stupid or alternatively that he is very clever. (Smart money goes with the second of these two possibilities.) See my post What's the difference between judges and geeks? (April 2010).
2. A common purpose of a stupid question is to prompt a useful answer or insight. Socrates used to ask dumb questions to make his pupils think more deeply about some subject - this technique is known as maieutic (from the Greek word for midwife).
3. Where a group is required to come to some judgement, such as a jury trial, a member of the group may request clarification on some point, not because she is personally unclear about this point, but because she believes some other member of the group may be unclear. (So for example, if one jury member kept talking about religious belief, another member might pose a question to the judge to confirm that religious belief was not relevant to the case.)
4. This particular case raises challenging legal questions that have not been tested in court for a very long time. Where the defence of marital coercion relies on a private and unrecorded exchange between husband and wife, the interpretation of such common phrases as "reasonable doubt" may become problematic, as does the fine line between inference and speculation. A stupid jury might not have been troubled by such ambiguities, and the judge clearly expected them not to be troubled. @davidallengreen (Jack of Kent) affirms that "we should not be shocked that a jury dares to ask basic questions; we should be concerned that juries do not ask basic questions more often."
5. If the judge offers an opinion about the jury's competence without being aware of the discussion and group dynamics that may have given rise to the jury's questions, this appears to be based on speculation rather than inference. It's a fine line, of course.
@WikiGuido describes the jury as 12 cretinous men (and women). I strongly disagree with his post, which has provoked a number of perceptive comments. Here's mine.
As a number of people here have already pointed out, the questions don't indicate that all the members of the jury were idiots. The questions could be explained by the hypothesis that some members of the jury wished to use the judge to settle internal arguments with other members of the jury. However, we don't know what happened in the jury room, and any conclusions about the intellect of the jury members based on these questions would count as speculation rather than inference. (The distinction between speculation and inference was relevant to this case.) As for drawing conclusions about the jury members' intellect based on their racial background or religious affiliation, this is merely bigotry.
Even if we regard the asking of these questions as a sign of stupidity (which I don't), the stupidity would attach to the group rather than the individuals. A stupid group or organization will often be composed of intelligent individuals who fail to agree. In this case, the group involved in this process comprises twelve jury members and one judge, and any intelligence or lack of intelligence is surely an emergent property of this group of thirteen people.
Ten questions posed by Vicky Pryce jury (BBC News 20 Feb 2013)
David Allen Green, What Pryce justice (New Statesman 21 Feb 2013)
Richard Moorhead, Is the trouble with juries, juries? (21 Feb 2013)
Joshua Rozenberg and David Allen Green, Should jurors have to take a literacy test? (Observer 23 Feb 2013)
Stefan Stern, Actually, the Vicky Pryce jury did its duty admirably (Guardian 20 February 2013)
Richard Veryard (ed) Greek Tragedy (Storify)