Both empiricism and rationalism have weaknesses. The scientific method contains bias and reduces complex systems to smaller parts that are insufficient to explain the complex system. The rationalist perspective bases the knowledge on innate knowledge that is assumed and not verified. Both methods have limitations, therefore, it is impossible to gain knowledge. 
On the other hand, the skepticism view holds that every person should be an inquirer who is still looking for the truth and is never satisfied. Because knowledge is impossible, skepticism is the best way to gain knowledge with human constraints.
There are truths that are not deniable. They can be addressed through inferential rules. If there are two chairs in the room, there are two chairs in the room. If one has the experience with the content that there is something green in front of him, then there is something green in front of him. By observation and reason, humans can gain knowledge and undeniable truth.