In my recent post on voting for politicians, I stated that voting solely on a politician is a vote of trust. Trust that they are sincere in their views and trust that they will be able to execute on their promises. With friends, we gain this trust over time by observing behavior in different situations. If a friend speaks of loyalty, are they there when you need help? How well do they perform at work or execute in cases where they are responsible for something? Whether this trust was built consciously, it exists in some measure for everyone you know. Can we reasonably extend this trust to our favorite politicians?
Like all good yes-no questions, the answer is "it depends". Breaking it down, it helps to check how much of a politician's behavior we have really seen. For an incumbent, we get to live the post-script of an election campaign. Their face graces our screens on any newsworthy occasion and their slights instantly make headlines. We can keep a mental, or these days digital, record of how many promises they've kept and weight those against our personal values. The longer the incumbent is in power, the more behavior we see and the wider variety of situations we see handled. Whether friend or foe, there accumulates enough data points to form an opinion on how well they wield power. But what of the rest of the candidates?
After losing an election, most candidates fade away into obscurity. I imagine they go to the same island for respite as Tupac or my favorite barista when I'm out of town. Yes, some political pundit or poli sci major friend may keep tabs on the goings-on of daily politics, but for most the next time you'll hear of the candidate is through election or scandal. All the campaign promises made and all the values stood for stand untested. There is no data available on how they would perform in power, no data upon which to build that deeper level of trust. What remains is only a vague hypothetical of the leader that could have been.
In practical terms, this effectively means that voting based on politicians is a vote of confidence for the incumbent. Voting for the incumbent is a vote based on trust earned, voting against is a vote based on trust lost. The specifics on who you choose in the latter scenario is necessarily based on a much weaker form of trust, one based on belief rather than evidence. It's important to keep this asymmetry in mind when there is no counterfactual. The decision harkens to the old Irish proverb, is it better the devil you know, or the devil you don't?