_Appeal to General Belief_, in which an appeal is made to general or universal belief, although the same may be unsupported by proof. This is quite common, but is no real argument. The common opinion may be erroneous, as history proves. A few centuries ago this argument could have been used in favor of the earth being flat, etc. A half-century ago it was used against Darwin. Today it is being used against other new ideas. It is a fallacy by its very nature. _Appeal to Ignorance_, in which an appeal is made to the ignorance of the opponent that his conviction may follow from his inability to prove the contrary. It is virtually no argument that: "So-and-so must be true, _because you cannot prove that it is not_." As Brooks says: "To argue that there is no material world, because we cannot explain how the mind knows it to exist, is the celebrated fallacy of Hume in philosophy. The fact that we cannot find a needle in a haystack is no proof that it is not there." _Introduction of New Matter_, also called _Non Sequitur_, in which matter is introduced into the conclusion that is not in the premises. Hyslop gives the following example of it: "All men are _rational_; Socrates is a man; therefore, Socrates is _noble_." De Morgan gives the following more complex example: "Episcopacy is of Scripture origin; The Church of England is the only Episcopal church in England; therefore, the church established is the church that ought to be supported." Other fallacies, resembling in some respects those above mentioned, are as follows: _Fallacy of Ambiguous Terms_, in which different meanings of the same word are used to produce the fallacious argument. As Jevons says: "A word with two distinct meanings _is really two words_." _Confusion between Collective and General Meanings of a Term_, of which Jevons says: "It would be obviously absurd to argue that because _all_ the books in the British Museum Library are sure to give information about King Alfred, therefore any particular book will be sure to give it. By '_all_ the books in the British Museum Library,' we mean all _taken together_. There are many other cases where the confusion is not so evident, and where great numbers of people are unable to see the exact difference." _Arguing from the Collective to the General_, in which the fallacy consists of arguing that because something is true of the whole of a group of things, therefore it is true of any of those things. Jevons says: "_All_ the soldiers in a regiment may be able to capture a town, but it is absurd to suppose that therefore _every_ soldier in the regiment could capture the town single handed. White sheep eat a great deal more than black sheep; but that is because there are so many more of them."