In decision-making problems, several methods exist in the literature. This paper shows how abductive reasoning can be a useful approach to deal with incomplete information. Our contribution proposes a model based on fuzzy gradual rules and fuzzy observations and operating in two steps. In the first step, we construct abductive hypotheses by using an inference method based on mathematical properties of generalized modus ponens. These hypotheses are not uniquely defined. This is why in the second step, we define two types of criteria to construct the best ones according to the given observation. These criteria are, respectively, the similitude and the coherence, which we propose to study in detail in this paper.