  The biostatistician Richard Royall is a particularly lucid defender of likelihoodism (Royall 1997).  He maintains that any scientifically respectable concept of evidence must analyze the evidential impact of E on H solely in terms of likelihoods; it should not advert to anyone's unconditional probabilities for E or H.  This is supposed to be because likelihoods are both better known and more objective than unconditional probabilities. Royall argues strenuously against the idea that incremental evidence can be measured in terms of the disparity between unconditional and conditional probabilities.  Here is the gist of his complaint: