Bias and Abduction in Political Reasoning

“When we consider the blood on the knife block, the victim’s handwriting on the grocery list, and the faint aroma of lemons on the divan, we must conclude that the killer was none other than the cook, Mrs. Shropshire.”

This is the sort of reasoning Sherlock Holmes does: taking stock all of the available evidence, and coming to the most reasonable conclusion about what happened or what will happen. It’s often called “inference to the best explanation.” Philosophers call this type of reasoning “abduction”–as opposed to deduction and induction, that is, not the kidnapping kind. We use abductive reasoning all the time: I come back to my apartment and my wife isn’t home. She hasn’t responded to my text, it’s a gorgeous day, and her running shoes are missing, so I conclude she must be out for a run.

​Or perhaps she’s been abducted (the kidnapping kind).

​It’s worth taking a second to think about abductive reasoning, because it’s often mistaken for bias. There’s admittedly a lot of similarity between these two. Both are ways of arriving at conclusions. But while abduction takes into consideration all of the relevant facts and constructs a reasonable account that holds all of them together, biased judgment skips this fact-gathering phase and jumps to conclusions based on a narrow set of facts and pseudo-facts.

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I’ll give an example. Let’s say I’m an unreasonably distrustful husband, and I’m perennially suspicious that my wife is having an affair. I come back to my apartment, she isn’t there, and I immediately conclude she’s cheating on me. I don’t even consider the possibility that she’s out for a run, and I fly into a jealous rage. This is biased judgment; I’m hastily assuming that what I’ve discovered conforms to my prior suspicions, and I’m ignoring more reasonable explanations that account for more of the evidence.

​The difference between bias and abduction is that abduction seeks out all the relevant evidence, while bias latches on to a few bits of evidence and excludes all the rest. Abduction is open to revision in light of new evidence, while bias is for the most part not open to revision. Bias is not always incorrect, of course, nor is abduction always correct. Say I notice my wife's running shoes are gone and I conclude she's is out for a run, but in fact she’s thrown her running shoes in a dumpster and is now eating an entire cheesecake at the Cheesecake Factory. In this case, I’ve arrived at a reasonable but incorrect conclusion, and later when I learn more information I will revise my beliefs about my wife’s whereabouts.

Now, I want to make this distinction clear because often, when two people interpret a situation differently, it’s not necessarily the case that either are making biased judgments. It’s possible that they have different information in mind that they consider relevant.

Take, for example, President Trump’s recent decision to rescind DACA. According to official statements from the Trump administration, this move is an attempt to restore power to Congress to make immigration laws, aimed principally at undoing an “unconstitutional exercise of authority by the executive branch.” According to many interpreters, however, this is a move motivated by racial prejudice, and is principally aimed at appealing to Trump’s base by vindictively chipping away at Obama’s legacy. Are people who subscribe to the latter interpretation simply showing their liberal bias? Perhaps, but not necessarily. A case could be made that, from the evidence, this is inference to the best explanation.

Consider the fact that only months ago President Trump signed two executive orders, the so-called “Muslim Ban” or “Travel Ban,” making immigration law without involving Congress. When those efforts were impeded, Trump’s administration repeatedly expressed frustration with the system of checks and balances, with policy adviser Stephen Miller even commenting “the powers of the president to protect our country are very substantial and will not be questioned.” To date, Trump has signed executive orders at more than twice the rate of his predecessor. Given this evidence, it is hard to believe Trump is overturning Obama’s executive actions primarily for the sake of restoring the separation of powers.

When one takes into account the numerous times Trump and his team have accused immigrants of criminal tendencies, the fact that Jeff Sessions mentioned keeping America safe even though DACA enrollees have committed no felonies, and this administration’s history of targeting Obama-era legislation without substantive justification, it is reasonable to conclude that this decision is more about nativism, fear of immigrants, and playing to anti-Obama sentiment than about separation of powers. One does not need to have an anti-Trump bias to put together the clues in this way.

I said before that abduction can often look like bias. Imagine if Sherlock Holmes walked into a crime scene, announced, “The cook did it,” and then left. Even Watson would probably say, “Hang on a second, Sherlock, what do you have against the cook?” Holmes typically explains his reasoning to show how he reaches his conclusions, and these explanations are crucially important. In the eyes of onlookers, an explanation can be the difference between rationality and irrationality, between abduction and bias.

So when one person says, “Trump is doing this to restore checks and balances because he cares about the Constitution” and another person says, “Trump is doing this because he wants good ratings and will appeal to base anti-immigrant and anti-Obama sentiments to get them,” this is not necessarily a clash of bias versus bias, nor of bias versus obvious fact. These are different conclusions that people can arrive at, with different levels of plausibility. To compare which explanation is more plausible, interlocutors sometimes need to make explicit the evidence that their conclusion accounts for. This is hard to do, especially in 140 characters or less, hence we often read conclusions without reading any of the reasoning that supports them. Contemporary political discussions seem like a stalemate between competing biases because they are all accusations and no evidence. We hear “It was the cook!” but we never see the blood on the knife block or stop to smell the lemons.

The lesson from all of this is elementary: when you are confronted with an explanation you disagree with, rather than jumping to an accusation of bias, present the evidence that does not square with that conclusion and offer an explanation that accounts for more of the facts. You and your interlocutor may find that there are pieces of evidence you each had not considered before. People are quick to accuse one another of bias, but by reasoning together we don’t simply identify bias but overcome it.