You should respect your parents by obeying their laws. Therefore, you should respect your city by obeying it laws. This is an example of circular reasoning. Clarity and distinctness are reliable criteria for knowledge because we can prove that a good God exists from the clear and distinct idea we have of God as a good being. This is an invalid syllogism.
All men are mortal.
Socrates is mortal. Therefore, Socrates is a man. The following causal relation expresses a necessary condition. In order to be eligible for that scholarship, you must be a 3.0 student. The following causal relation expresses a sufficient condition.