Limiting words are used to limit the scope of the idea being asserted. Limiting words, such as "possibly," signify that the author and researcher is merely putting forth a scenario that could describe the phenomena being researched instead of stating flatly that the idea does describe the phenomena. Limiting words are used as tentative language in academic papers to signify that, though the current research may not definite, the idea is being considered.
Softening verbs show the reader that the researcher is drawing and inferring from his own research. "Appears" and "indicates" are two prime examples of softening verbs. These verbs are chosen because the author is looking at data or phenomena and describing in his paper what he sees and thinks. The author's intent is not to lay out blanket statements in a work of research.
Modal language differentiates between what is actual and what is possible. Modal words include "may" and "could." Modal language is used as tentative language to describe a conclusion drawn in the research as a possible explanation for the phenomenon being studied.
Philosophy regularly makes use of tentative language for many of the same reasons as academia. Philosophy is creating an argument for a specific assertion, but that assertion cannot be categorically proved true or false, so tentative language is used. People often use tentative language in everyday speech as well to soften the impact of the statements being made.