Q&A: 'All the More So' and 'A Fortiori'
'All the More So' and 'A Fortiori'
Question
Hello, is there a difference between "all the more so" and "a fortiori"? Is there a difference in the content of the inference and in the form of the inference?
Answer
I haven’t checked this systematically, but it seems to me that "all the more so" is a popular-language expression for an a fortiori inference (especially when one is not dealing with deriving halakhic conclusions from Scripture). Usually this is an a fortiori inference from one given case to another (whereas a Talmudic a fortiori inference is based on three elements).
Discussion on Answer
In my opinion, no. What you mean is the a fortiori type of "a maneh is included within two hundred." But not every "all the more so" is of that kind.
Do you happen to have an article about those types of a fortiori inference ("a maneh is included within two hundred")?
I have articles that deal with the question of whether such an a fortiori inference can be refuted. See, for example, the articles for the portions of Acharei Mot and Emor, nos. 81-2, here:
https://drive.google.com/drive/folders/0BwJAdMjYRm7IRmM4RGd0dG9zWU0
Would it make sense to say that "all the more so" is an inference where what is learned is, in some sense, contained within the source case, whereas an a fortiori inference involves two different matters that are connected only by the logic? At first glance, that seems right to me based on several places, though I haven’t checked it carefully.