The Unverifiable Assumption of Radiocarbon Dating: a second statement of

There are two basic assumptions in the carbon 14 method. One is that the carbon 14 concentration in the carbon-dioxide cycle is constant. The other is that the cosmic ray flux has been essentially constant--at least on a scale of centuries.

 Kulp, J. Laurence, "The Carbon 14 Method of Age Determination," The Scientific Monthly, 75 (November, 1952), 261.