where there are two possibilities (aka disjuncts),  

and the confirmation of one is  incorrectly taken to deny the other.

This fallacy follows the format: "A  or B is true; A is true; therefore,  

B is not true." It's a fallacy because  both A and B could be true simultaneously.

Everyday example:

A person said, "It's raining outside, so either  I take an umbrella or I will definitely get wet;  

since I'm taking an umbrella, it's  impossible for me to get wet."

This statement implies a false dichotomy:  either taking an umbrella or getting wet,  

suggesting these outcomes are mutually exclusive.

However, this is an oversimplification.  In reality, taking an umbrella doesn't  

inherently prevent the possibility of getting wet,  

as other factors like wind could  still lead to one getting wet.