Has the form of if--then; written as: If A then B or A>B 

Modus

A > B

A 

B 

Modus

Tollens 

A>B

~B

~A 

A>B

B

 A 

I have water, so I must have hydrogen 

A>B

~A

~B 

I don't have water so I don't have hydrogen. 

A>B

B>C 

A>C

If a goalie gets the soccer ball to the sweeper, then to the forward, the forward goes beyond defenders, then the forward will get the ball past the goalie. 

It's either this one or that one (deny one). 

A vs. B

~A  

B 

A vs. B

~B  

A