Historical linguists would disagree. The problem here is (European) Portuguese phonology, which is a big part of what makes intelligibility between Portuguese a

Historical linguists would disagree. The problem here is (European) Portuguese phonology, which is a big part of what makes intelligibility between Portuguese and Spanish so asymmetric. The written languages are quite close for the most part (though there are obviously vocabulary, such as Portuguese having borrowed quite a bit of French vocabulary and Spanish having greater Mozarabic influences, and morphosyntactic differences, such as the Spanish a-accusative), those are pretty surmountable. It's phonology that messes things up, which the heavy reduction of unstressed vowels in EP and the palatalisation seen in BP make Portuguese a lot more difficult for Spanish speakers to understand than the other way around. I know some BP and ES (though I'd never call myself remotely fluent in either), but I find EP quite difficult to follow, FWIW. I wouldn't be at all surprised if the mutual intelligibility of BP and Spanish is higher than EP and Spanish.