 Jeffrey proposes a now-standard solution that replaces conditionalization by a more flexible process for credence change, called Jeffrey conditionalization. Recall that conditionalization has a defining feature: it preserves the credence ratios of the possibilities inside new evidence E while the credence in E is raised all the way to 1. Jeffrey conditionalization does something similar: it preserves the same credence ratios without having to raise any credence to 1, and also preserves some other credence ratios, i.e., the credence ratios of the possibilities outside E. A simple version of Jeffrey’s norm can be stated informally as follows (in the style of the tutorial  section 1.2):