Contextual conditional sentences depend on the speaker's and hearer's state of knowledge. Among them there are predictive conditionals which convey the idea of a lack of knowledge; they are not factual and therefore cannot be classified as true or false. They are not connected with the present situation. In hypothetical conditionals the protasis is also not knowable or predictable. That may be contrasted with epistemic conditionals where protases generally contain an assumption that is indirectly known to the speaker or potentially to everybody else, and, moreover, it is contextually grounded. Indirectly is a key word here, since that is the reason why the conditional marker if is used. There are also conversational conditionals (speech acts and metatextual ones) which are used mainly as linguistic devices to express the speaker's uncertainty or the polite character of the utterance. These are also contextually based and cannot be understood without some preliminary knowledge.

Most commonly such sentences are based on the assumption that the hearer has already got some information concerning the content of the if-clause. Let's consider the following:

1. [1] If he's making calls now, I'll come later.

2. [2] If Peter is not in his office, he went for the meeting.

3. [3] If it's four, we're late.

4. [4] If I ever met him, I have completely forgotten about it.

The protases of these sentences must be contextually grounded or given otherwise they would not be properly understood.