I recently started to learn about logic, so far I've learnt this two ways of logical proofs.
As far as I know, they are two kinds of methods. One is a proof calculus in which logical reasoning is expressed by inference rules closely related to the "natural" way of reasoning, the other is based on the idea of proof by contradiction.(Please correct me if I made mistakes).
It suddenly occurs me that is there something semantic tableaux can/cannot do while natural deduction cannot/can, and how should I tell whether I should use semantic tableaux or natural deduction if I want to be more effective?
Thanks.