The Three Party Argument (from an academic source)

If the people want responsible parties, they need to have a third party, since rational parties seek votes, and responsible parties carry through with their political promises: Three parties would push the current two parties to differing parts of the right/left continuum, forcing them to become less rational and more responsible. We observe that Israel is an example of Coalition government, which is not subject to gridlock. The reason I say no gridlock is that Israel is capable of a pre-emptive strike now and then. My question, since I cannot penetrate this from Israeli news is this: Is Israel's government and example of responsible parties? Do Israel's parties carry through on their political promises? This question is so far un-answered.