The greatest, most unbiased knowledge of our existence and our passage through it comes from this two-step alliteration of the scientific method—conjecture and criticism.
Conjecture is a guess. Most guesses stand on the shoulders of the most tested theories, explanations that vary little. These guesses break new trail from these outposts into mystery. Conjecture is imaginative, creative, a frontier. Sometimes a consilience of ideas from other domains, at others an improbable opportunity in dissatisfaction, in all cases, a hypothesis launching us to a higher ledge.
Criticism is more than debate, the method debunks madness. Most often evidence is gathered, experiments designed, models run, rinse and repeat. There is no way to ensure criticism is maximally effective, but it offers a brute force way to bust bias and create venues for updated conjectures to fill the gaps.