Jim's Logic Proof for driving as he does.
Jim had studied enough logic to know he must keep going, but not enough to know he was supposed to drive down the center of the road. 01. L v R In the past, Jim had noted that either the left lane is closed, or the right lane is closed. 02. R > Ml And he knew that if right lane is closed, then one must take the left lane 03. L > Mr And also he knew that if the left lane is closed, then one must take the right lane. 04. L & R But Jim can now see that both lanes are closed ahead. ---------- 05. L Which means, the left one is closed (4, Simplification) 06. R And, too, that the right one is closed. (4, Simplification) 07. Mr So, Jim deduces he must take the right lane. (3,5, Modus Ponens) 08. Ml v Mr That, or he must take the left one. (7, Addition) Jim has correctly reasoned that he must take either of the two lanes, and so he yells, "Onward!" and punches the gas, as the above picture shows. Yet with a bit more study, Jim would have reasoned as follows: 09. Ml "But I must likewise take the left lane." (2,6 Modus Ponens) 10. Ml & Mr "Therefore, I must take the left land and the right lane!" (7 & 9 Conjunction) Such contingencies of life show the value of studying logic.