As for contradictions;


Identifying Contradictions
''Most people find it difficult to identify contradictions in an explicit way, but it is important to learn to do so. Here is an explicit definition of a contradiction together with the proper method for identifying one.

Contradiction
Def.: To be logically committed to the assertion of some statement, S, and its denial, not-S, at the same time.
ID.: Identify the statement that being both asserted and denied.
To see how to identify contradictions properly, consider the following conversational example.

Mrs. Beeble: You have been absent from class 11 times this month. You fail. Goodbye.
Butch: What? That's impossible! The class only meets twice a week.
Mrs. Beeble: True, but you have missed it 11 times nevertheless.
Butch: That doesn't make any sense. You can't be absent from a class on days that it doesn't meet.
Mrs. Beeble: You're saying you weren't absent on those days?
Butch: That's right..
Mrs. Beeble: So you were here?
Butch: No!
Mrs. Beeble: You are wasting my time. If you weren't here, then you were absent. Goodbye''