I looked through the nice paper by Tarski On the Calculus of Relations. In the beginning he touched a motivation behind Theory of Relations but this part was not clear to me (page 1, very beginning):
De Morgan clearly realized the inadequacy of traditional logic for justification... witness his famous aphorism, that all the logic of Aristotle does not permit us, from the fact that a horse is an animal, to conclude that the head of a horse is the head of an animal
As far as I understood from wikipedia, the problem with Aristotle logic is that it does not contain singular terms and does not allow to talk about a singular object. It allows to talk about multiple objects such as 'all Socrates', 'some Socrates', 'no Socrates' and sounds awkward, but does not allow to talk about one particular singular 'Socrat'. 1) Is this right?
2) Did Aristotle logic restriction motivate Theory of Relations?? To me it seems unlikely, since I don't see the connection (unfortunately). So what did motivate development of Theory of Relations?