If something is not explicitly prohibited, is it permitted?

Question

I had this disagreement with someone. I said that everything is 'b'chezkas' heter, and is mutar unless there is a source that assurs it. He said that everything is assur unless you find a source that its mutar.

Can you provide a source or proof one way or another?

(According to him, I would think that fruits like mangos or avacados should be assur to eat.)

edit - it seems that he was joking, but I'm still curious if there is a source in gemara or mefarshim about this. (One can argue that no source is needed, as it is logical, but like I said, I'm curious.)

Answer 1

The Mishna in Yadayim 4:3 states that R. Yishmael asserted that R. Elazar ben Azaria must bring a proof to his position because whoever is stringent has to bring a proof:

א"ר ישמעאל אלעזר בן עזריה עליך ראיה ללמד שאתה מחמיר שכל המחמיר עליו ראיה ללמד

The Tiferes Yisrael there explains that anything for which we do not know a reason to prohibit is by default permitted, since the Torah does not delineate everything that is permitted but delineates things that are forbidden:

שכל דבר שלא נדע טעם לאסרו מותר הוא בלי טעם דלא הזכירה התורה דברים המותרים כולן רק דברים האסורין

R. Joseph Messas was asked if the rule that the stringent party must bring the proof is an accepted rule, and he responded by quoting the Tiferes Yisrael and saying that the implication is that this is true even for Biblical laws:

Otzar Hamichtavim Vol. III # 1,373

שאל כבודו במכתבו על מה דקי"ל בדברי סופרים כל המחמיר עליו להביא ראיה אם זה כלל מוסכם או לא

תשובה זה ודאי כלל מוסכם הוא ומסתבר שכל המוסיף באסורים עליו להביא ראיה וכמ"ש במס' ידים פ"ד משנה ג' א"ר ישמעאל לר"א בן עזריה עליך ראיה ללמד שאתה מחמיר שכל נמחמיר עליו ראיה ללמד ע"ש וכתב שם הגאון בעל תפארת ישראל וז"ל שכל המחמיר וכו' שכל דבר שלא נדע טעם לאסרו מותר הוא בלי טעם דלא הזכירה התורה דברים המותרים כלם רק דברים האסורים עכ"ל יעו"ש משמע מזה דאפי' בד"ת על נמחמיר להביא ראיה ויש לי אריכות בזה במקום אחר ושלום

Answer 2

Yes , tos gitin 2b says that it requires 2 witnesses to prohibit something versus one to permit- the question is that logically it should be the other way around!' The achronim answer that everything has a chezkas heter so to prohibit would require 2 versus to permit would only require one

Answer 3

Rashi to Yevamos 88a, s.v. ואמר ברי לי writes that the source that עד אחד נאמן באיסורין, a single witness is believed regarding prohibitions, is learned from the fact that one is permitted to eat other people's food.

The Torah never explicitly states that one is allowed to eat other people's food (and in fact some other Rishonim reject Rashi with the suggestion that if this were the only source, perhaps one would actually only be allowed to eat other people's food with two witnesses that it was kosher), and yet Rashi assumes that this is the basis for generalizing a halachic principal that one witness is trusted for prohibitions. Seemingly the fact that the Torah never prohibited it is strong enough evidence that it is permitted.