Sentence:  On the <WSD>theory</WSD> before us , such relief would be groundless , for in that suffering itself there was nothing bad at all , and hence in its nonoccurrence there would be nothing to be relieved about . 
Meaning of the word marked with <WSD> tags:  a well-substantiated explanation of some aspect of the natural world; an organized system of accepted knowledge that applies in a variety of circumstances to explain a specific set of phenomena