I'm asked to show that the following argument is valid:
P1) $[E \lor (L \lor M)] \land (E \leftrightarrow F)$
P2) $L \rightarrow D$
P3) $D \rightarrow \neg L$
C) $E \lor M$
Here is my work (so far):
P2) $L \rightarrow D$
- $\neg(\neg L) \rightarrow D$ Premise
- $L$ Premise
- $L \rightarrow D$ 1, Substitution
- $D$ 2, 3 Modus
I'm not sure.
I know you need to use the rules of inference like modus ponens or converse fallacy, but I'm confused because it doesn't look like any of the forms I've learned.
Thanks