Both the Notre Dame Economics and Philosophy programs are first class, I don’t think Notre Dame will spend too much time questioning your motivation to transfer (of course there has to be a clear and meaningful statement in that respect), yet will be focussing on fit and what you can bring to Notre Dame, the reason the “Why Notre Dame” aspect of your application will be of utmost importance.
The reason I asked for the major interest simply was to make sure you were not intending to transfer into MCOB or the COE, which would have been a major hurdle.