<p>I've never seen anyone put "CV is a statistical blog" exactly, although I may have missed it.  I often put something like "CV is a Q&amp;A site for questions about statistics (machine learning, etc)" in a comment to a thread that is about something like 'how to convert data from wide to long in R', which is about software / coding rather than statistics.  I may sometimes shorten that to "... about statistics" (without the parenthetical expansion) when the context suggests to me that it may be acceptable shorthand.  I certainly <em>do not</em> mean that machine learning, data mining, or data visualization are off topic here; I simply take them to be assumed or that it is unnecessary to state them in those cases.  </p>

<p>Regarding what is on topic here, that is an issue that has been discussed extensively several times on meta.CV (you can read through some of the threads tagged under <a href="https://stats.meta.stackexchange.com/questions/tagged/on-topic">on-topic</a>, e.g.).  For what it's worth, my own criterion has always been straightforward: <em>What does the OP need explained?</em>  If it is a statistical (machine learning, etc.) concept, it belongs here, if not, it belongs elsewhere.  A statistical concept need not be theoretical (depending on how strictly one wants to define that term).  </p>

<p>The biggest issue concerns questions about software use, particularly coding.  That is already on topic on <a href="https://stackoverflow.com/">Stack Overflow</a>, where questions get good answers very fast.  From the point of view of the SE system, it isn't best to have questions equally on topic on multiple sites.  That leads to cross-posting, among other problems, and is analogous to the problem with duplicate threads (cf., <a href="https://stats.meta.stackexchange.com/a/4728/7290">here</a>).  To some extent, that will always exist, as the sites are living things, but where it can be avoided, it probably should.  </p>

<p>As far as your other topics, the history of statistics has long been considered on topic here, and philosophy questions are often fine.  It is certainly true that what is on topic or not will never be perfectly consistently enforced because the system is managed by the collective efforts of many different people.  It is also true that in the past the boundaries were less clear and somewhat in flux.  On occasion, old threads that should be off topic are closed, or sometimes are 'locked' to preserve their historical value.  </p>
