The root cause of such a logical error is sometimes failure to realize that just because P is a possible condition for Q, P may not be the only condition for Q, i.e. Q may follow from another condition as well.
ðə ɹˈuːt kˈɔːz ʌv sˈʌtʃ ɐ lˈɑːdʒɪkəl ˈɛɹɚɹ ɪz sˈʌmtaɪmz fˈeɪlɪɹ tə ɹˈiːəlaɪz ðæt dʒˈʌst bɪkˈʌz pˈiː ɪz ɐ pˈɑːsᵻbəl kəndˈɪʃən fɔːɹ kjˈuː, pˈiː mˈeɪ nˌɑːt biː ðɪ ˈoʊnli kəndˈɪʃən fɔːɹ kjˈuː, ˈaɪ.ˈiː. kjˈuː mˈeɪ fˈɑːloʊ fɹʌm ɐnˈʌðɚ kəndˈɪʃən æz wˈɛl.