Church gave three reasons for this requirement. First, it adheres to extant standards of mathematical rigor. Secondly, reasoning purely by the rules of the logistic system is safer than reasoning about any interpretation one may wish to adopt, because—as is discussed in 2.2—the object language is set up using an informal meta-language that is “so elementary and restricted that its essential reliability can hardly be doubted if mathematics is to be possible at all” (1956a [BE: 415]). Finally, it allows one to draw a precise distinction between form and content: