We tend to explain behavior in terms of internal disposition, such as personality traits, abilities, motives, etc. as opposed to external situational factors.
"We believe that what others do reflects who they ARE, while what WE do reflects our circumstances." A proven bias. See: https://en.wikipedia.org/wiki/Fundamental_attribution_error . One would think this is critical to our thinking about politics, though that's not clear. "If I struggle to pay the bills, it's cause of my heart attack and the bad economy; YOUR struggle to pay the bills is due to the fact that you're lazy and/or irresponsible."