All dogs are animals. Cats are animals. Therefore, all cats are dogs.
What is an invalid syllogism?
A father tells his daughter she shouldn't start smoking because it's unhealthy. She replies, "You used to smoke, so your advice is worthless."
What is an ad hominem fallacy? (personal attack)
Partner A: "You never help with the chores."
Partner B: "You're not so great at doing the chores either, because you never put your car all the way in the driveway!".
What is a red herring fallacy? (new evidence used as a distraction from the topic)
If we allow students to have deadline extensions for one interview, soon we'll have to allow them for everything, and deadlines will become meaningless.
What is a slippery slope fallacy?
Either something is made with sugar, or it is not a dessert. Omelettes are not made with sugar. Omelettes are not dessert.
What is a valid syllogism? (If your object refutes the 'either' statement [from the major premise] in the minor premise, then you have to accept the 'or' statement from the major premise.)
What is a straw man fallacy? (ignoring the position of the other and substituting a distorted position)
Someone takes a vitamin supplement and then recovers from a cold the next day. They conclude the vitamin caused the recovery, without considering other factors like their immune system naturally getting better.
What is a post hoc, ergo propter hoc fallacy?
Giving up nuclear weapons weakened the United States' military. Giving up nuclear weapons also weakened China. For this reason, it is wrong to try to outlaw firearms in the United States today.
What is a non-sequitur fallacy?