Flaw in transitivity

[voodoochild]

Experts,

Last night, I had the following discussion with my friend.

She said that cancer is death, and death is part of life. Therefore, cancer is part of life. Is this true? I believe this relationship is intransitive. Plus, it doesn't make any sense--how could cancer be part of life of someone who doesn't have cancer. However, I couldn't explain what's wrong here.

I have come back to this forum after a long time, with a hope that I will get help. I owe my admission and graduation to the help I have received here. I am truly indebted to the experts here.

[Francis O'Rourke]

It is very easy to misapply formal logic to informal language. This is a good example of that.

If we were to interpret your friend's statement as All and only cancer leads to every death, then your friend's reasoning would be correct. Of course, this interpretation of your friend's statement is verifiably false. You yourself recognized this when you stated that there are people who never develop cancer. If you can show that a necessary premise is false, then the argument falls apart. We don't see this on the LSAT, since the test does not try to measure your knowledge of facts, but it is useful to keep in mind in real life.

On the other hand, that interpretation I provided above was a bit extreme. In every day life it is a mistake to take such a extremely formal interpretation of statements. If I heard a friend of mine saying 'cancer is death,' I would interpret that as an exaggerated way of communicating 'cancer is a terrible disease that causes too much suffering and often leads to death.' This is probably a closer to what most people mean when they make the claim that your friend did. In this case there is no certain or necessary connection between cancer and death.