But can we claim an absolute ability to extricate ourselves from our own biases? We need to, if we are to personally rely completely on rationality.
Here I will explore these thought a little, and suggest we look at one reason why we cannot remove our biases completely. Essentially the reason is fashion. Or what Germans call 'zeitgeist'. Fashion can make us focus and exclude other possibilities.
I like Roger Penrose's wonderful 'The Road to Reality'. He dances seemingly effortlessly around the broad and varied terrain of higher mathematics. The adventure of higher maths is set out as an open invitation for the reader. Interestingly for me, Penrose also muses thoughtfully on the interactions of mathematics with physics and with the human experience of consciousness.
Well into the book, Penrose notes that, in his opinion, some areas of currently orthodox astrophysics are rooted in questionable assumptions. He addresses, for example, inflationary theory (p753). This is the now widely held assumption that the early universe underwent a period of rapid inflation. He looks at this theory with some gentle questioning skepticism.
Later in the same book, Penrose discusses likely further progress in astrophysics and cosmology. He makes the point that certain theories become fashionable and channel research effort, whether theoretical or experimental.
It is obvious that ideas in astrophysics are complex and multi-faceted. They are often based on multiple assumptions. Truly representative experimental validations are normally not feasible. It is not unreasonable to question existing conclusions when these were made under demanding constraints. Even if the conclusions have become widespread orthodoxy.
Further than this, Penrose notes that once an idea has taken hold, it tends to self-re-enforce. An idea or 'meme' is defined and established. A blinkeredness can then very easily take over. An exclusive orthodoxy develops. Other approaches and theories are denigrated. Penrose looks at how this tendency outworked in recent history with string theory. A survey was made of then-contemporary papers concerning the perplexing area of quantum gravity. At the time the survey was taken, for this subject, there was a very strong bias toward research papers based on string theory, compared to papers based on other approaches. It is then easy to see how the popularity of the theory strengthens, at the expense of research into others. Is this warranted and what are the results for effective investigation of the original subject, here quantum gravity? Human factors are probably at play here! (this means that,for the reductionist, the conscious attributes cosmology and evolution gave us in actual fact start to subvert our ability to enquire accurately!).
How much of the fashionability of, say, string theory, is warranted? Does its present popularity represent the accuracy of the theory? That is an open question in general. Theories can become popular because they are already fairly popular. There may be a culture and an inertia in academic circles, and a fear of being found dissenting, but wrong. There may be a further fear of triggering the real fear of unorthodoxy in others, especially if the others have power over you, maybe regarding funding decisions or powers of appointment to academic positions. It is true that this tendency to fit in might correct itself after a period of time, as the chosen theory succeeds or fails. However as the issue being researched gets more complex, the required correction might get less realizable. There may also be the fear that the entire big picture of, in this example, astrophysics/cosmology as it stands ,might come tumbling down. Can we allow that to happen? If not, why not? What if we think it is best to hide our doubts, maybe even from ourselves? Similar concerns might apply to the geology/anthropology/evolutionary biology picture. Or indeed religious/political/philosophical beliefs. In all cases, at least some of the details may be highly questionable. When there are so many variables to fit together, do we really have the big picture correct? Our worldviews need to be subject to this sort of scrutiny if we are claiming to be champions of reason..
Such problems mean the scientific method is most reliably applied to arenas where all facts can be carefully defined and/or controlled, and multiple experiments performed. This is the arena routine engineering uses. It is about proof of the pudding. Would you really want to be the test pilot of an aircraft built using principles with a similar level of abstraction and lack of rigour to those associated with cosmology or evolutionary biology? Or do you just want to believe it all for reasons you are hiding from yourself?