Question: what was the main cause of the irish civil war
[{'answer': 'Anglo - Irish Treaty', 'provenance': [{'wikipedia_id': '15214', 'title': 'Irish Civil War', 'start_paragraph_id': 94, 'start_character': 476, 'end_paragraph_id': 94, 'end_character': 497, 'bleu_score': 1.0, 'section': 'Section::::Consequences.:Legacy.\n'}]}, {'provenance': [{'wikipedia_id': '15214', 'title': 'Irish Civil War', 'start_paragraph_id': 2, 'start_character': 4, 'end_paragraph_id': 2, 'end_character': 521, 'bleu_score': 0.8693302810135771, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11912440183832715460}, 'section': 'Section::::Abstract.'}]}]