I have to write 5 syllogism and i need to find out if the ones i wrote are valid or invalid is this correct.?

Question

1. all zebras are striped animals. no zebras are polar bears. Therefore, no polar bears are striped animals. (valid)

2. all clowns are funny individuals. Some sad people are clowns. Therefore, some sad people are funny individuals. (invalid)

3. Some sticky substances are yucky things.
All taffy is a sticky substances. Therefore some taffy is a yucky thing. (invalid)

4. All items made of gold are expensive items. Some rings are items made of gold. Therefore, some rings are expensive items. (valid)

5. All flies are winged creatures. All butterflies are winged creatures. Therefore, all butterflies are flies. (invalid)

Answer 1

You have made a few mistakes. A valid argument MUST be true if the premises are true. Take your first example:

1- This is actually an INVALID argument. Even though all zebras are striped, we don't know that all striped animals are zebras. Some of the striped animals may be other things... maybe even polar bears. You can make this argument valid either by changing your first premise (to ALL striped animals are zebras) or your conclusion (to SOME striped animals are not polar bears). Or you can just mark it invalid. :p

2- This is actually a VALID argument. It may not make sense, but if we ASSUME that all clowns are funny and that some of them are sad, then the only logical conclusion is that some sad people are funny. If you change the second premise (to no people are funny and sad) then it becomes invalid. Likewise you can change the conclusion to any number of things to make it invalid.

You do have all the others correct, though. Party on!

Answer 2

1 Is invalid. Your first statement does not apply to polar bears one way or the other. All zebras are striped. No polar bears are striped. Therefore, no polar bears are zebras. That is valid although it doesn't tell you much.

2 is valid.

3. is invalid, correct.

4. is valid, correct.

5. is invalid, undistributed middle term. Correct.