Give us good reasons to believe the conclusion, all the premises must be truth and the conclusion must follow from the premises
VALID ARGUMENT
If Barack Obama is President of the USA, then Michelle Obama is First Lady.
Barack is President of the USA.
Therefore, Michelle is First Lady
If the premises are true, the conclusion can´t be false. The true of the premises guarantee the true of the conclusion.
STRONG ARGUMENT
EXAMPLE
I am Adrian's best friend. I'm sure of this because she told me so, and I know she wouldn't lie to her best friend
DEFINITION
If all the premises are true, the conclusion follow with high probability (above 50%). Assume all the premises are true, even if one or more is clearly false.
