感觉 means to feel; however, both 感 and 觉 both mean to feel by themselves. Why does the word 感觉 exist then? I've noticed that a lot of words are redundant.
"感", more objective, the feeling that surroundings impose on you. "冷感", "热感"
"觉", more subjective, the feeling from your heart (/mind/senses) about surroundings. "味觉", "视觉"
Yes, they are quite similar, and in some cases, they both mean "feel/feeling".
But in some other cases, you can find the difference by comparing "感到" and "觉得".
"我感到房子在摇动", I have a feeling that the house is shaking.
"我觉得房子在摇动", I think the house is shaking (maybe not, actually).
In fact, there are quite a lot of chinese words made of characters with similar meaning, like 奔跑/游泳/旋转/图画/增加. Two of the reasons I know:
- it can avoid ambiguity with the same pronunciation (which reminds me of the different characters with same pronunciation in Japanese).
- it improves the symmetry and fluency of a sentence, as most words in chinese are made of two characters.
actually this group of words is called 同义复合词 Synonymous compound
1.make the definition more clear. if you only use one character, it may have many different meanings.
2.enlarge the meaning. eg: 牙齿，牙 and 齿 both mean a certain part of the tooth, but when combined, it means the whole group of teeth.
3.increase rhythm. in some ancient poems, there are character restrictions, like 5 or 7, so in order to reach 5 or 7, people use 同义复合词. these words now becomes our everyday use.