Karl Popper. No way around it - there is no scientist in this world who is completely free from bias. There is no scientist in this world who can completely divorce themselves from their beliefs and motivations. There is no scientist in this world who is free from mistakes. Even the very formulation of the scientific method itself is based on human perspectives and ways of proceeding.
Science tries to be objective but no way of gathering information is completely unbiased because one needs a perspective in order to make a hypothesis and decide what one is going to pursue. Every single human being approaches a matter of study with some sort of preference, and a scientist is no exception.
Science makes a point of being unbiased in the way it does
research. In experiments, neither the subject nor the experimenter knows what
changes have been made to the subject’s regimen. This “double blind” step is
deliberately taken to eliminate bias. Then, when a scientist’s experiment is
finished, it is published in a scientific journal, so that people with opposing
viewpoints can be heard. This is another step intended to make sure bias is eliminated. Scientists are proud of the way they
investigate the world, with methods that encourage scientific detachment and
Any knowledge gained through science is built by questioning and controlling for bias, which means that of all ways of gaining knowledge, science is the least biased method. This does not mean that science is a perfect and objective way of gaining knowledge, but it is the most stringent field in negating the bias of individual researchers.
Science is a tool used to make assumptions about the reality of the world we live in using observation and falsification to obtain knowledge. Science is also the collective knowledge of humans over thousands of years and currently presents the most up to date view of reality based on collective knowledge. Science does not rely on anything but observation and allows itself to adapt and change with new information.
If anything, science is the most unbiased way of obtaining knowledge. Why is this? Because you need to provide either proof or evidence to even be considered. How, in any way, is that a bias? This holds true for all of science. It seeks out truths with empiracle evidence. Not bias.