For Renaissance Aristotelian natural philosophers, ideally knowledge was certain and based on syllogistic demonstration. Many Italian scholars, such as Agostino Nifo, Pietro Pomponazzi, and Niccolò Cabeo, considered this ideal as inapplicable to the field of meteorology. Rather, because of the accidental nature of meteorological phenomena and the inherent irregularity of the weather, they believed that causal explanations of meteorology were largely conjectural, provisional, and probabilistic. Several of these natural philosophers applied the standard of "saving the appearances" to the field of meteorology because of the difficulties involved in making accurate observations. This lower epistemological standard contributed to the willingness of Aristotelians to revise meteorological theories and deviate from Aristotle's own positions.