I was trying to put together the opinion of the Rosh on these topics, and had some difficulty.
It seemed that the Rosh learns that the key difference between the two is that Taam K'ikar is when the heter is fully permeated by the wine, whereas Heter Mitztareif is where there is only part (or none) of the heter that absorbed the wine.
The Rosh writes (37a d"h Im Yesh Bo Kdei l'Tzaref) that if the wine permeates the entire heter, there is no added stringency of heter mitztareif over taam k'ikar.
Based on this, I surmised that the Rosh holds that taam k'ikar means that even the heter becomes issur, since otherwise there is a clear stringency even when the heter fully permeates the issur.
But I wondered, is it possible to hold taam k'ikar and not heter mitztareif. I initially thought the answer was yes, since the point of taam k'ikar is that even though the issur is mixed it's not bateil, and heter mitztareif is particular to when the issur stands on its own. So each has its own chiddush. But the description of mishras seems clear that there could be absorption of the issur and it still counts because of heter mitztareif. And the Rosh makes it clear that heter mitztareif is the bigger chiddush (end of 37a). So that makes it sound to me like heter mitztareif assumes that the part which absorbs the issur is certainly a problem, and adds that even the part without the issur joins.
The issue with this is that the Rosh seemingly argues (37b d"h v'Im Kesheirah etc.- v'Yihyeh Chat'as v'Gi'ulei Aku"m Shnei Kesuvim ha'Ba'im k'Echad v'Heter Mitztaref Neilef b'Chol Isurim mi'Nazir, v'Nireh Li Kivan sheha'Davar Shakul Mistabra Tfei le'Esor Ta'am k'Ikar etc.) that there is a possibility for heter mitztareif without taam k'ikar (ie. by all issurim except nazir where we have both), and just because there's nothing pushing either way we assume the other way. Wouldn't it be impossible to assume the other way - once you say heter mitztareif, how can you not say taam k'ikar?
If we would say that taam k'ikar just teaches that there is not a bitul of the issur, this wouldn't bother me since then the main chiddush is that something that's absorbed is not bateil. But since we seem to assume that it all becomes issur, then it seems we take the issur of an absorption as a given (as for example in the case of kzayis b'kdei achilas pras), and just want to know whether the whole heter becomes assur or only the portion that was permeated by the issur.
Thanks!
Kol tuv,
Sender Klein
Sender Klein, New York, USA
1) It seems to me that the Rosh maintains consistently that Ta'am k'Ikar is more powerful than Heter Mitztaref l'Isur. That is why he writes (end of 37a) that the Rabanan do not hold of Heter Mitztaref but do hold of Ta'am k'Ikar when the taste of the wine spreads throughout all of the bread. So the Rabanan clearly hold Ta'am k'Ikar and not Heter Mitztaref. This is what the Rosh (end of 37a) means when he writes that Heter Mitztaref is a bigger Chidush -- that one can hold Ta'am k'Ikar and not hold Heter Mitztaref.
2) The Rosh (37b) does not write that there is a possibility of Heter Mitztaref without Ta'am k'Ikar. He writes the opposite, that it is more logical to prohibit Ta'am Kk'Ikar than it is to prohibit Heter Mitztaref.
Kol Tuv,
Dovid Bloom