Bacon is often studied through a comparison to his contemporary René Descartes. Both thinkers were, in a sense, some of the first to question the philosophical authority of the ancient Greeks. Bacon and Descartes both believed that a critique of preexisting natural philosophy was necessary, but their respective critiques proposed radically different approaches to natural philosophy. Two over-lapping movements developed, “one was rational and theoretical in approach and was headed by Rene Descartes; the other was practical and empirical and was led by Francis Bacon.” They were both profoundly concerned with the extent to which humans can come to knowledge, and yet their methods of doing so projected diverging paths.
On the one hand, Descartes begins with a doubt of anything which cannot be known with absolute certainty and includes in this realm of doubt the impressions of sense perception, and thus, “all sciences of corporal things, such as physics and astronomy."  He thus attempts to provide a metaphysical principle (this becomes the Cogito) which cannot be doubted, on which further truths must be deduced. In this method of deduction, the philosopher begins by examining the most general axioms (such as the Cogito), and then proceeds to determine the truth about particulars from an understanding of those general axioms.
Conversely, Bacon endorsed the opposite method of Induction, in which the particulars are first examined, and only then is there a gradual ascent to the most general axioms. While Descartes doubts the ability of the senses to provide us with accurate information, Bacon doubts the ability of the mind to deduce truths by itself as it is subjected to so many intellectual obfuscations, Bacon's “Idols.” In his first aphorism of New organum, Bacon states:
“Man, the servant and interpreter of nature, does and understands only as much as he has observed, by fact or mental activity, concerning the order of nature; beyond that he has neither knowledge nor power.”
So, in a basic sense the central difference between the philosophical methods of Descartes and those of Bacon can be reduced to an argument between deductive and inductive reasoning and whether to trust or doubt the senses. However, there is another profound difference between the two thinkers' positions on the accessibility of Truth. Descartes professed to be aiming at absolute Truth. It is questionable whether Bacon believed such a Truth can be achieved. In his opening remarks, he proposes “to establish progressive stages of certainty.” For Bacon, a measure of truth was its power to allow predictions of natural phenomena (although Bacon's forms come close to what we might call "Truth," because they are universal, immutable laws of nature).