Social programs, tax cuts and the deficit

You know, I hear Leftists like Rachel Maddow talk about how soldiers have made sacrifices while people at home get tax cuts, so we put the war on the deficit. What I never hear about is how social programs are not only never cut, but expanded while we are at war. Somehow, all of this social spending does not cause the deficits (because it takes place in an alternate universe apparently) but allowing people to keep more of what they earn does lead to higher deficits. How does that work?