C# tends to default everything to the minimum scope necessary. This is a nice convention and quoted in Skeet's book (C# In Depth, p 224 "Note/Trivia"):
[Properties are the] only place where “private” is required—Everywhere else in C#, the
default access modifier in any given situation is the most private one possible. In other words, if something can be declared to be private, then leaving out the access modifiers entirely will default it to being private. This is a nice element of language design, because it’s hard to get it wrong accidentally: if you want something to be more public than it is, you’ll notice when you try to use it.
