Final answer:
Intuition is usually considered the least reliable method of obtaining knowledge because it isn't based on empirical evidence and cannot be tested or verified.
Step-by-step explanation:
The least reliable method of obtaining knowledge is typically considered to be intuition. While intuition involves knowing or sensing something without the use of rational processes, it is not always accurate. Knowledge obtained through empirical research, like systematic observation in scientific studies, tends to be much more reliable because it is based on evidence and can be tested and replicated. Compared to methods such as case studies or testimony, intuition does not necessarily rely on observable evidence and often cannot be empirically verified, making it the least reliable in the context of scientific inquiry and rigorous knowledge acquisition.