(a) translate the argument into symbolic form and (b) determine if the argument is valid or invalid. You may compare the argument to a standard form or use a truth table.
If Nicholas Thompson teaches this course, then I will get a passing grade.
I did not get a passing grade.
∴ Nicholas Thompson did not teach the course.
See
http://www.jiskha.com/display.cgi?id=1310596763
To translate the argument into symbolic form, we can represent the statements as follows:
P: Nicholas Thompson teaches this course.
Q: I will get a passing grade.
The argument can now be written as:
If P, then Q.
Not Q.
Therefore, not P.
To determine if the argument is valid or invalid, we can use a truth table.
P | Q | If P, then Q | Not Q | Therefore, not P
----|-----|--------------|-------|-----------------
T | T | T | F | F
T | F | F | T | F
F | T | T | F | T
F | F | T | T | T
Looking at the truth table, we see that whenever the premises are true (P is true and Q is false), the conclusion is also true (not P is true). Since the argument is valid in every row of the truth table, we can conclude that the argument is valid.