About the question So, by 'type of questions', I really mean this from an ontological perspective. I imagine there is a complete set of (type of) questions, and thus any question that ever was or will be asked will be of one type or the other belonging to such a set.

A problem In trying to form such a set containing all question types, is there a way we could know for sure that we have covered all possibilities? Say we never had a concept of time, we could thus never ask 'when' something happened. Furthermore, if this was the case, it's not like we could just conclude 'oh, we must be missing the concept of time!', because obviously we would have started with such a concept to make that conclusion to begin with.

My attempt at an answer In trying to derive an answer myself, I have come up with 6 types. These are: when and where (relating to spacetime), what and who (identification and personhood i.e human identification), why (motive) and how (causality).

A problem with the answer It seems as if though however, that many questions can be rephrased to give the same meaning, but using different question types. For e.g, 'how does a ball drop to the earth' vs 'why does a ball drop to the earth'. The answer to both seems to be gravity. So there seems to be a problem of interchangeability. Now I know that why and how aren't always interchangeable, such as 'how did he murder' vs 'why did he murder', but when they are, that seems to be problematic.

Summary So, how can we go about forming the set of all question types, and can we know when we have done so? Furthermore, why is it that some question types seem interchangeable when such types are of a different nature to each other? Maybe it's just a matter linguistic confusion?


2 Answers 2


As I lack reputation, I will formulate my thoughts on this as an answer.

First of all, the questions "how does a ball drop to the earth" and "why does a ball drop to the earth" yield different answers. The answer to "why" is obviously gravity. In regard to how does the ball drop to earth, I'd say "with velocity increasing by the square law. Also perpendicular to the surface, if there are no other forces involved."

How generally has a description as an answer. Why demands a reason. I don't think those two are interchangeble.

I think we can neglect "when", as it is a subset of where. Time is just another dimension. So while not common in everyday use, the question "where did the event happen" could yield the answer "At (x,y,z,t), where (x,y,z) are spatial coordinates and t is a point in time". Or in a less abstract way "At central station at 5.14pm". So asking for "when" is actually just retrieving a part of the "where"-answer.

Also, who is just a special case of what, as it only refers to people. So instead of asking "Who went to the party?", with the answer "Mark", you could ask "What went to the party", with the answer "A person with the name Mark".

This leaves us at Why - Reason Where - Place and time What - Object/Person How - Description

It is impossible to know if we miss something unknown.

  • Thanks for the answer, you've made some nice critiques, but that seems to be all there is. It hasn't actually gotten down to the meat and bones of what the question is about... Commented Sep 25, 2016 at 16:35
  • I think I reduced it down to four. Also I disagree with interchangeability. Commented Sep 25, 2016 at 17:33

Every kind of question that is not solely a 'what-question' can be expressed as a 'what-question':

  • Questions that ask "when?" are questions that ask "at what time?"
  • Questions that ask "where?" are questions that ask "at what place?"
  • Questions that ask "why?" are questions that ask "for what purpose?"
  • Questions that ask "how?" are questions that ask "in what way? or "what made?"
  • Questions that ask "who(m)?" are questions that ask "what person?"

In terms of the Aristotelian tetradic taxonomy of causes:

  • 'How-questions' inquire about efficient cause. (e.g. "How is she?" inquires about the way in which she is feeling as an implicit effect of whatever might cause her to feel a particular way. "How did the ball fall to the floor?" inquires about the cause of the particular effect of a falling object such as the gravitational force of nature.)

  • 'Why-questions' inquire about final cause. (e.g. "Why did he do that?" inquires about the purpose guiding/motivating whatever it is that "he" did. "Why did the ball fall to the floor?" inquires about the purpose guiding/motivating the falling of the ball to the floor such as, for example, someone wanting to drop the ball.)

  • 'What-questions' inquire about formal cause and/or about material cause. "What is it?" inquires about the identity of "it" and, therein, inquires about formal cause. "Of what is it made? inquires about the identity of the parts of a whole.

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