When I was in college and graduate school in the 1970s and 80s I learned the scientific method. There was a lot of focus on being objective. While I never questioned the concept I do remember that I preferred other words similar to it, such as impartial or disinterested. In the 80s and 90s, objectivity came under great pressure from critics who rightly pointed out that one cannot suppress their feelings or emotions or biases while doing research. Today, the basic idea is to understand these biases and mitigate against them if possible. Or, maybe we just live with the lack of impartial arguments.
Objectivity is a modernist idea. It wasn’t part of the Enlightenment agenda; usage of the word gets its peak around 1970, noting that the last swing to a higher peak after 1980 is likely the post modern counter attack. [click on image for better view; use the back button to return]
Prior to this, the word Impartial was the main idea during the Enlightenment
In the early 19th century the word Disinterested was fairly common.
As scientism faded in the later part of the twentieth century so does objectivity. Subjectivity and Conflict of Interest get more usage as post modern discussions get going. With Subjectivity being the flip of Objectivity it too is falling into disuse.
The real concern in our new romantic era is conflict of interest and the partiality of many observers and commentators.
Note: All Ngrams are done for the period 1700-2008 with a smoothing of 3 for English.