Should I use a pie chart?

My opinion on pie-charts and poor visualization comes from years of studying data visualization, not ignoring it. Would you argue that Tufte doesn't value data visualization since he holds the same views?

Ok, let's start with the most obvious. How about a chart showing how much of a pie has been eaten? There's a bell curve of useful applications for pie charts that moves away from that, and the shoulders might be pretty tight, but it's absurd to say that's it's simply wrong for all applications. Even all moderately common applications.

> the relationships in a table are more clearly represented in most all cases

Nonsense. It might be easier to compare specific values, but people simply needing to parse a column of digits makes it the wrong choice for many applications. If your communication problem involves communicating values, a table is a great way to go. If your communication problem involves quickly communicating relationships between a handful of elements, a table is the least effective way to do that. Not everybody has a use case for all data that is benefited by seeing precise values. You can't pretend that's not true by just ignoring that other use cases exist, or that other audiences aren't like you. Go ask an investor if they'd always prefer tables to box whisker graphs, or a statistician if they'd always prefer tables to data plots. Similarly, pie charts are great for showing roughly how several elements comprise a whole. If you wanted to show that something used about 21% of the budget, something else used about 29% of the budget, and something else used about 50% of the budget, putting that in a pie chart quickly communicate the relationship between those values far better than putting those values in a table, bar chart, or many other visualizations. The audience matters. That wouldn't be useful to accountants, but it might be useful to give a a company-wide audience a rough idea of why some executive action was enacted, for example. The purpose of data visualizations is to present things in ways that reduce the cognitive load of parsing values while still communicating the overall purpose. A box and whisker graph wouldn't be useful for that visualization. And a to the vast majority of people, table would be less efficient at communicating that idea than a pie chart.

> Information density also doesn't imply that you most be conveying a lot of information, it relates to the efficiency of your use of visual space.

Without a specific communication problem to solve, you can't determine what the best use of space is. You're expecting every audience to parse information like you do. You're wrong. That's why visual designers exist. The oft-repeated design maxim of avoiding wasted space is something only non-designers say because it's much easier to gauge and reason about than the most effective use of space. Optimizing for economy of space isn't even useful in many contexts. When the purpose is efficiently communicating something, giving the primary message focus often means giving it a lot of space, be it conceptually or physically.

> There are no instances (aside for the other example of a clock plot) where the relationships in your data (since you don't want to use information) are not more clearly conveyed with a list then a pie chart.

Ok, how about how many slices of pie have been eaten?

> I've spent quite a bit of time working with and talking to visual designers and have yet to meet one who think pie-charts are an effective tool for visual communication.

Frankly, people like you-- really strong opinions on visual design but have never practiced it, don't know the methodologies, don't know what most people's use cases are for data visualizations, and generally don't understand why everybody doesn't like looking at numbers as much as you-- are probably people that most experienced visual designers don't want to talk about charts with. Regardless, you could tell me that everyone you've ever met hated pie charts and that still wouldn't be worth any more in this context than just saying it's your arbitrary preference.

Working as a long-time developer, I did encounter a few tutorial-drunk designers who tried to assert their ideas about proper software development in dev meetings they happened to be at. As a developer, it was always like "ok there fella. We'll take your opinion into account. Now go play in photoshop." It was pretty rare, though. But I'm continually astonished by the number of developers that assume their amazing superpowers of reason and logic make them qualified to tell any credentialed experienced professional how their field works.