If the lawful use of a commodity that is used for both lawful and unlawful purposes predominates over its unlawful use, is it permissible to sell it, or is it a condition that all of its uses be lawful, bearing in mind that it has been stated that it is permissible to sell refrigerators to disbelievers even if they use them to store unlawful things, and in other fatwas it has been stated that it is not permissible to sell if the seller knows that the buyer will use it for unlawful purposes?

It is permissible to sell refrigerators, mobile phones, and similar permissible items. The lawfulness of the sale is not affected by the fact that some people might use them for unlawful purposes, for the ruling is based on the predominant and original lawful intent. The jurisprudential principle states: "What is impermissible independently may be permissible dependently," and "What is tolerated incidentally is not tolerated intentionally." An example of this is the permissibility of renting a house to someone who might commit some unlawful acts therein incidentally, not primarily; thus, there is no sin upon the landlord.