There is a word in English which I forgot for the decision that people make that involves a mutual agreement made in the lack of communication . For example, if 2 people agree meet each other tomorrow and then they realize when not together that they had not specified the time and cannot contact each other, then the most common sense decision would be to meet at the noon. Similarly for the place, the most common choice could be the same place as the last time.
You might start with abductive reasoning which, in loose terms is described as guessing or "taking your best shot".
This Butte College summary of three types of reasoning (deductive, inductive, and abductive) has a fairly lenghty explanation of it, beginning with this:
Abductive reasoning typically begins with an incomplete set of observations and proceeds to the likeliest possible explanation for the set. Abductive reasoning yields the kind of daily decision-making that does its best with the information at hand, which often is incomplete.
Apparently, the single-word term abduction was coined by American philosopher Charles Peirce (sic) in his treatise "Abduction, Reason, and Science: Processes of Discovery and Explanation".
Peirce is also referred to as "the father of pragmatism", which brings to mind the word pragmatic. Pragmatic is defined in the Cambridge Dictionary Online as
solving problems in a sensible way that suits the conditions that really exist now, rather than obeying fixed theories, ideas, or rules
In loose terms, I might tell someone under the circumstances that you described that I was being pragmatic, but I might just say that I will have to wing it, or, under the circumstances, it looks like we'll be freestylin' today".
wing it To improvise; to make things up or figure things out as one goes; to perform with little or no preparation.
freestyle The practice of improvising scenes when making a film or performing a play. (This word has been repurposed to a very general and informal use as improvise.)
Of course, those last two are not meant to be serious answers to your question, but they could be used.
If you are looking for the decision making shared between two people without communicating, telepathy (or even abductive telepathy) comes to mind. But telepathy, if it exists, is described as communicating.
A related word, that does not involve communication is clairvoyance which means
Acute intuitive insight or perceptiveness. The supposed power to see objects or events that cannot be perceived by the senses.
Basically you are looking for the default.