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Confusion of Necessary with a Sufficient Condition

A causal fallacy you commit this fallacy when you assume that a necessary condition of an event is sufficient for the event to occur. A necessary condition is a condition that must be present for an event to occur. A sufficient condition is a condition or set of conditions that will produce the event. A necessary condition must be there, but it alone does not provide sufficient cause for the occurrence of the event. Only the sufficient grounds can do this. In other words, all of the necessary elements must be there.

Examples:

  1. Juan: "How do you think you'll do on our philosophy exam tomorrow?" Monique: "Great, I read all the books."  Juan: "Yeah but do you understand this stuff?" Monique: "I said I read all the books, didn't I?"
  2. Don't let all the talk about the necessity of exercise to a long life mislead you. Jim was a jock all his very short life.
  3. Who said food keeps us alive? Tom died a few days ago and he was not short of good food.
  4. I don't know why the car won't run; I just filled the gas tank.
  5. Why don't you want to spend your life with me? I love you, and am I not good to you?
  6. The counselor told me that if I wanted to graduate I must have at least 128 credit hours. Well, I've got that, but they're saying I won't walk this semester. How misleading!
  7. The job description said that they were looking for someone with a Master's degree. I've got my MA, but I cannot understand why they did not hire me.
  8. My high school English teacher told me successful people have extensive vocabularies. So, I've tried to learn a new vocabulary word every day since then. I should be a successful person soon.
  9. "If you want the chairman to like you," he said, "you'll have to show how impressed you are with his ideas." Well, I turned myself into an ego-stroking machine, but it's pretty clear I have yet to win him over.
  10. I've heard this ever since puberty: in order to fall in love with another, you have first to love yourself. This is such a crock! I have no trouble loving myself, bit I can't say I've ever fallen in love in my life.