I almost forgot: if you want to write about evidence, you should also read about it. A good place to start -- and finish? -- your reading is M. MacCrimmon & P. Tillers, eds., THE DYNAMICS OF JUDICIAL PROOF: COMPUTATION, LOGIC, AND COMMON SENSE (Physica- & Springer-Verlag, 2002) (vol. 94 in series STUDIES IN FUZZINESS AND SOFT COMPUTING, Janusz Kacprzyk, editor).
There is a bit of 'rithmetic in this readin' material. But there is also common sense there. You can't ask for more than that!