I used to be firmly in the one-space camp because my first intro to the subject was from Robin Williams _The Mac Is Not A Typewriter_. However, at some point -p

I used to be firmly in the one-space camp because my first intro to the subject was from Robin Williams _The Mac Is Not A Typewriter_. However, at some point -probably one of the regular resurrections of this debate on HN - I came across a convincing argument that the line of reasoning in that book is wrong; that it was actually common for typeset books to use larger spaces between sentences than between words and that when the typewriter was invented, the two space rule came about because that's what people were already used to seeing. I got so sick of all the arguments from ignorance that I decided to get empirical and have taken to examining the type in old books to see if there's any kind of consistency as you work back in time from the word-processor era to the typewriter era to the pre-typewriter-era. The problem is that I don't have access to enough old books to come to much of a conclusion. I have _The Works of Shakespeare_ from 1919 (MacMillan and Co.) and it definitely uses wider spaces between sentences than between words. This is true both in the fully justified text of the preface as well as in the ragged right of the plays. I also have a Webster's Dictionary from 1937 and it too uses wider spaces between sentences than between words. All the text is fully justified. However, virtually all modern books use the same width space between words as between sentences. Notice that I'm _not_ saying "one space" or "two spaces" because books are typically fully-justified and so it can easily be the case that all the spaces on a line are much wider than a single space character; it's just that the space between sentences is no wider than the space between words. Which brings me to what I feel like is usually ignored in these debates: justification. Professionally typeset works that get printed are almost universally fully justified. Everything else - typical word-processor output, the entirety of the web, etc. is left justified. if you're going to write an algorithm for full-justification you're going to have to mess with spacing and it doesn't seem entirely unreasonable to put a little more space between sentences than between words. Although presumably it's algorithmically simpler to treat all spaces the same way, especially if there aren't great rules for even knowing when a sentence ends e.g. "No, I expect you to die Mr. Bond".