Each of the four ways makes the same point for four different kinds of cause: first, cause of motion; second, cause of a beginning to existence; third, cause of present existence; and fourth, cause of goodness or value. The common point is that if there were no first cause, there could be no second causes, and there are second causes (moved movers, caused causers, dependent and mortal beings, and less-than-wholly-perfect beings). Therefore there must be a first cause of motion, beginning, existence, and perfection.
In Logic types of fallacy are firmly described thus: First the premises and the conclusion must be statements, capable of being true or false. Secondly it must be asserted that the conclusion follows from the premises. In English the words therefore , so , because and hence typically separate the premises from the conclusion of an argument, but this is not necessarily so. Thus: Socrates is a man, all men are mortal therefore Socrates is mortal is clearly an argument (a valid one at that), because it is clear it is asserted that Socrates is mortal follows from the preceding statements. However I was thirsty and therefore I drank is NOT an argument, despite its appearance. It is not being claimed that I drank is logically entailed by I was thirsty . The therefore in this sentence indicates for that reason not it follows that .