One clear exception to the affirmation that knowledge is better than the lack there of is the fact that people almost universally would rather not know about things that their significant others have done with previous significant others. Sure, from a rationalist point of view, it technically might be helpful for a man to know what his girlfriend has done with previous boyfriends because that knowledge could help him to better understand how enjoyable different things that he can do will be for her. However, such knowledge tends to result in fairly intense feelings of jealousy that are quite unpleasant. And so I have to concede that having such knowledge is not terribly blissful.

A less clear exception to my affirmation is the fact that when some people know about terrible things that are happening in the world, they feel awful about them. I completely do agree that there are things taking place that are absolutely appalling, but I think that the way to respond to such things is to provide help, not to feel guilt or other unpleasant emotions. There are places all around the world where one can provide volunteer services, and there are hundreds of well-run organizations through which one can make a donation to make a difference. Having an understanding of problems in the world and being able to do something to help is generally quite rewarding for people, and as such I do maintain that it is better to have knowledge of these situations than not to. But for the people who experience the unpleasant feelings, I can at least recognize your objections.

A final exception that I think is somewhat reasonable is the fact that many people experience feelings of jealousy by knowing about others who have things better than they do. Anyone who has ever worked with children knows that they are quite prone to experience such feelings when they know that another child is being treated better than they are. And I do accept that many adults experience such feelings as well. My claim, however, is that the real problem is inequity in the first place. Yes, definitely some people find it more pleasant to simply not know about inequity, and the exception here clearly applies to them. However, others do not like the fact that there just is inequity at all, and they would rather know about it so that they having the option of doing something about it if they choose, such as donating money to a lobbying group for progressive taxation. An additional comment, though, is that often in my experience people perceive things as inequitable when really they are not, and the feelings of jealousy would disappear by simply thinking more carefully about the situation, which begins again to sound like omniscience is bliss...

I do accept, by the way, that there are probably other exceptions that I have not thought of yet. If you can think of anything that I have missed, feel free to drop me an email.