Ireland is unique in Europe and the World for not having a left-right political divide. Civil war politics being a reason but also because the left have never been a strong cause or have had a strong base here. Historically the strongest left leaning party has been the Labour Party yet they only average 10% of the vote in most elections. On average left leaning parties manage together 20% of the vote in elections while the rest is carved up by centre right parties Fianna Fáil and Fine Gael and independents.
So why has there never been a strong left wing cause in Ireland?
-Civil war politics as already mentioned
-Irish society having an overall conservative outlook?
-The influence of the Catholic Church on society? Related to part 2
-The top left leaning party Labour constantly going into government with right leaning Fine Gael?
I think the left have had their chances to displace civil war politics in favour of a left right divide but circumstances dictated that it didn't happen. Like 1948 when a Fine Gael party on it's knees was saved by the split in the Labour Party and Clann na Poblachta being forced into a snap election when their relatively new organisation wasn't ready. Maybe Labour could have overtaken Fine Gael in 1969 but the red scare played up by Fianna Fáil(an example of Irish society being conservative) killed the Labour vote in rural Ireland and perhaps 1992 was a chance as well to overtake Fine Gael had Labour ran more candidates.