Necessity (the ninth of twelve things I love about philosophical logic)

from blog Home on consequently.org, | ↗ original
The next two thoughts are motivated by the two complementary aspects of contemporary research in logic, proof theory and model theory. As I try to emphasise to my students, there are two broad ways you can define logical concepts like validity. Following the way of proofs, an argument is valid if there is some proof leading from the premises to...