Consider the following premises. p_2 -> t. forall x_18: P_18(x_18). ~t. Can we infer p_2 from them?
 From forall x_18: P_18(x_18) we can infer P_18(a_18). Finally, from p_2 -> t, ~t we can infer ~p_2, which contradicts p_2. Therefore, the answer is no.