Illogical tests were used to see if someone was a witch.
One of the most popular ways to test if someone was a witch was to throw them in a body of water (lake, river, etc.). If she floated, she was a witch. If she drowned, she wasn't one (though she would die). Another test was to prick a wart, insect bite, or mole with a needle. If the person felt pain, they were a witch.