About empiricists and one question to the empiricists

The empiricists see that the only source of conception is the senses. If the senses can not reach something then we will have no picture and conception of that thing. Whoever loses one's senses will lose one's knowledge. For empiricists the scope of knowledge is limited to sense perception. Even the function of the mind is limited to sorting, composing, generalizing and tidying up the results of these sensory perceptions. Reason is by no means independent and even intellect can not create (intizha) concepts that have no material properties at all. In the empirical view, reason is not something immaterial and can not even create immaterial concepts such as the concept of being, causation, probability and others. The empiricists say that experience shows a person who loses the senses of vision for example he will never know anything related to vision, for example he will never know what it is green or red and other colors.

However, the one question here that I want to say is suppose that what the empiricists say is true, then how do the empiricists get the conviction that the mind is not something independent? That the mind can not create (intizha) concepts that are not material at all? Have empirics experimented on this? If it can not be experimented from where the basic rejection of reason?

We agree that the senses are one of the stages in how to gain knowledge, but is it enough with the senses? If so how do we know that sugar tastes sweet it is sweet? is sweetness a purely sensory perception or is there other knowledge that gives us belief about sweetness? If there is how that form of knowledge is?