of facts, many more than any competing explanation, then it is likely to be true." Statistical inference McCullagh states this form of argument as follows: There is probability (of the degree p1) that whatever is an A is a B. It is probable (to the degree p2) that this is an A. Therefore, (relative to these premises) it is probable (to the degree p1 × p2) that this is a B. McCullagh gives this example: In thousands of cases, the letters V.S.L.M. appearing at the end of a Latin inscription on a tombstone stand for Votum Solvit Libens Merito. From all appearances the letters V.S.L.M. are on this tombstone at the end of a Latin inscription. Therefore, these letters on this tombstone stand for Votum Solvit Libens Merito. This is a syllogism in probabilistic form, making use of a generalization formed by induction from numerous examples (as the first premise). Argument from analogy The structure of the argument is as follows: One thing (object, event, or state of affairs) has properties p1 . . . pn and pn + 1. Another thing has properties p1 . . . pn. So the latter has property pn + 1. McCullagh says that an argument from analogy, if sound, is either a "covert statistical syllogism" or better expressed as an argument to the best explanation. It is a statistical syllogism when it is "established by a sufficient number and variety of instances of the generalization"; otherwise, the argument may be invalid because properties 1 through n are unrelated to property n + 1, unless property n + 1 is the best explanation of properties 1 through n. Analogy, therefore, is uncontroversial only when used to suggest hypotheses, not as a conclusive argument. See also Antiquarian Archaeology Archival research Auxiliary sciences of history Chinese whispers Historical criticism Historical significance Historiography List of history journals Philosophy of history Recorded history Scholarly method Scientific method Source criticism Unwitting testimony Footnotes References Gilbert J. Garraghan, A Guide to Historical Method, Fordham University Press: New York (1946). Louis Gottschalk, Understanding History: A Primer of Historical Method, Alfred A. Knopf: New York (1950). . Martha Howell and Walter Prevenier, From Reliable Sources: An Introduction to Historical Methods, Cornell University Press: Ithaca (2001). . C. Behan McCullagh, Justifying Historical Descriptions, Cambridge University Press: New York (1984). . R. J. Shafer, A Guide to Historical Method, The Dorsey Press: Illinois (1974).