If you can read the following only once and understand it, consider yourself part of a very small minority: "It is the dilemma of the box within a box or, in the case of arbitration, the authority as to the decision as to the authority to make the decision." That is "arbitrability" in a nutshell; not a simple concept. Indeed, at oral argument in First Options of Chicago, Inc. v. Kaplan, the confusion occurred to a U.S. Supreme Court Justice.
Michelle St. Germain,
Arbitrability of Arbitrability, The,
2005 J. Disp. Resol.
Available at: https://scholarship.law.missouri.edu/jdr/vol2005/iss2/11