Wikipedia tells us that Experimental Philosophy (X-Phi) is:
an emerging field of philosophical inquiry that makes use of empirical data—often gathered through surveys which probe the intuitions of ordinary people—in order to inform research on philosophical questions. This use of empirical data is widely seen as opposed to a philosophical methodology that relies mainly on a priori justification, sometimes called “armchair” philosophy by experimental philosophers.
So what makes X-Phi experimental is the use of data rather than (presumably) data-less a priori reasoning. This is confusing. Even when employing ‘pure reason’, philosophers use data – if only the data of their senses, experience and consciousness. Would anyone deny that Descartes used data when he came up with the Cogito? That it was the data of his own experience doesn’t make it less valid qua data.