There is no widely agreed upon list of the most important intellectual questions. Nor even a well-known attempted list, upon which people disagree. As far as I can tell there is hardly even such a list for any specific field. I don’t know of even a single person who has such a list. The closest things I know of are Hilbert’s list of important mathematical problems, published in 1900, a few less well knows lists by later mathematicians, some of Edge’s Question Center lists, and a recently compiled list by of problems in social sciences.

Perhaps you can find (and please send me) examples to prove there are such things, but my point remains that such lists are not common or popular. It seems that we hardly even discuss what the most important questions are. I don’t know off the top of my head what I think they are, even for the fields I am especially interested in. I could probably come up with a list if I thought about it, but it is surprising that I have not sufficiently done so already. I have even less idea how other people would answer. This seems strange. The idealistic intellectual’s supposed self-imposed quest is to work out these big important problems, or chip tiny bits off the sides of them. It seems it would be useful to keep in mind what we think these problems are.

I’m tired, so instead of compiling such a list, I’ll just give you one question. Why are such lists not more popular? I don’t know. But here are some ideas in no particular order:

1. ‘Important questions’ is just too vague a category.
   This seems false; there is generally public agreement about which additions to human knowledge are significant advances. If it is too vague, it could be narrowed to either questions of practical importance or those with theoretical interestingness.
   .
2. ‘Questions’ are too vague an entity.
   How important a question is just depends on how abstract you make it, and questions abstracted too far are useless. ‘How can we make the universe perfect?’ is presumably the question of most practical importance, and is not interesting at all. I don’t think this is really a barrier though. I’d be surprised if our intuitive notion of what is an optimally abstracted question did not serve. Or we could just pick a rough level of abstraction and stick to it.
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3. Nobody cares about intellectual progress on big ideas. Intellectuals are all about signaling their academic ability, and asking questions doesn’t do that.
   This seems false and immaterial. For someone to make a list it need not be that most people are motivated by intellectual progress on big ideas. Only a small fraction need be motivated. And they need not be motivated by intellectual progress on big ideas alone – there are other kinds of attention one could get from such an activity. A person could demonstrate confidence in his judgement and informedness, like having an opinion on the best wines or films can in other circles does. Knowing enough about enough things to write a decent list would be quite a feat I think. Many intellectuals write blogs, and I expect compiling such a list could get an amount and type of attention not unlike a period of blogging, even if the list was collected from the opinions others. I would expect some section of intellectuals to be motivated even if the majority are not.
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4. Such a list would not actually be useful, since whoever had a say would use their answer to look good, or advertise a problem that they are already working on.
   This is arguably illustrated within some of the near-examples I listed. However it should be possible to get around this, for instance by each person having to nominate a number of questions, or by the authors being sensible to the effects on their credibility if they so blatantly self-promote.
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5. Most intellectuals are already working on something, and prefer to think that it is one of the most important things. So they would be actively opposed in the same way that doctors are opposed to finding out and publicising which hospitals are least likely to kill you.
   This is supported by the observation that whenever you begin a new subject at college you are introduced with the assurance that anthropology for instance really is the bedrock upon which all other puny scientific pursuits are built. But if this is a force against scrutiny of importance, it is not so obviously so that it should have put off anyone from trying to make such a list.

Why do you think we don’t keep lists of the big questions?