From the very start of this excellent dystopian novel concerning a future world where so many choices are taken away from us as humans and people are forced to live in a world without memories and colour, it is clear that deceit and keeping things to yourself are options that are not open to any of the citizens. Note how in the time of sharing in the family of Jonas, although he would have preferred not to share, he did not have a choice:
Jonas sighed. This evening he almost would have preferred to keep his feelings hidden. But it was of course, against the rules.
However, in Chapter Nine when he receives his folder with more details about his new role as Keeper of Memories, he is given a list of regulations that completely overthrow all that he has learnt in his society. The last regulation specifies explicitly that Jonas "may lie." Jonas reflects on how he has been instructed about the "precision of language" and how carefully he has been brought up to avoid "unintentional lies" such as "I'm starving." Now, however, Jonas is free of this restriction and this freedom troubles him.
When Jonas receives his list of rules and learns that he can lie, he reacts with fear and revulsion. He does not want to be able to lie, and the thought of lying is unsettling. He realizes that the community’s rules against lying are ironic, because everything that everyone says and does is recorded. It is impossible to lie about anything other than feelings, so the rules against lying are really just another way of controlling feelings. Jonas continues that if he has permission to lie, others might too. The rule against lying is completely unenforceable.
Sameness requires that no one has strong feelings about anything. This is why the community has a ritual for describing and dismissing them. Jonas’s community also has rules against lying because lying produces awkwardness, and every rule in the community is design to prevent discomfort. If someone was caught in a lie, both the liar and the person being lied to would feel bad. This kind of thing is to be avoided at all cost.
Before his role as the Receiver, Jonas had been taught that lying was against the rule. After he received his new instructions, he found that he could lie. Upon reading his instructions, he realized that he could not know if the adults in the community were lying to him or not, even if he asked them whether they lied. He learned that rules may not always be followed or we may not even know if they are followed.