The Limits of Logic

Sun, 11 Dec 2016

I suppose it is inevitable, being alive in 2016, that I’ve had a lot of thought-provoking conversations this year.

Perhaps unlike many people, when I think about political issues, I am as fascinated by logic as I am of substance (I blame that on having done a Masters in Philosophy of Science!).  I am more inclined towards being intellectually honest than being right or convincing.  I don’t say that to boast - there are definitely times when being more confident in expressing my gut feelings would have led to better outcomes.  

Since so many people seem a bit perplexed at how others could possibly believe the things they do, I thought it might be useful to outline some of the reasons I’ve encountered why our beliefs are generally less logically convincing than we might think:

Ambiguous Language

One source of conflict relates to the language we use, and our definitions.  Quite often, when debating political issues, we use evocative, emotive language, which unfortunately can be ambiguous and carry baggage that we may not intend. It can make sense if we’re trying to rally the loyal troops, but it is going to be unhelpful if we’re trying to clear up a disagreement.

Examples of such terms from discussions I’ve had this year have been “racist”, “socialist”, “free market”, “establishment”, “Christian”, and “foreigners”.  If both people happen to mean the same thing by the language, that’s great, but we shouldn’t assume that will be the case.  

In these cases, I find it best to avoid loaded terms, and stick to simpler terms that say exactly what you mean, and be as generous as possible in interpreting what the other person is saying (asking questions where necessary).  Feel free to explain to the other person why, though you agree with the person’s intention, you feel that their words convey a message they don’t intend - they may choose to reword.

The Power of Evidence

I’ve heard a lot of concern raised about people’s unwillingness to accept evidence, and willingness to believe ridiculous things.

For many people, the way they seem to consider information is as follows:  if it backs up your desired argument, it should be considered proof; if it contradicts your desired argument, it should be ignored (either as a lie or as inconclusive).

In fact, I think of evidence as much more complex.  There is a spectrum of kinds of information.  Some can prove or disprove a point, but most information (particularly in politics) is a lot less conclusive, either for or against an argument.  It can be a useful exercise to ask yourself what information might be considered overwhelming evidence (both for and against) -  I’d suggest that if we’re honest, most non-trivial statements are just about impossible to prove, even with lots of data.

The Future is Unpredictable

The biggest struggle I face when debating politics is that none of us know what is going to happen.  With such an uncertain world, it is a rare decision that would prove optimal in every possible scenario.  

For example, I’ve heard some people who suggest that it is pointless to talk about the downsides of Brexit because it hasn’t happened yet.  This makes no sense - most of decision-making relies on making decisions under uncertainty.  

Decision theory tells us that we can deal with this uncertainty, by considering each outcome, and its probability.  While I agree this is sensible, I’m not sure that we can ever get our head around the infinite range of possibilities and their probabilities, let alone agree on them.  Inevitably we will end up making simplifications, ignoring certain outcomes.  

For example, with Brexit, I’ve been in several conversations where it has become clear that the other party thinks that a recession is more or less likely than I do, that the EU will be more or less generous, or that the prospects for the EU are better or worse than I think they are.  Even if we do our best to state our assumptions, there will be a point where we have to agree to disagree.

This is particularly relevant when the outcomes our significantly influenced by one person.  In the case of Trump’s election, we are all forming views of how he might carry out his role.  I’m not sure that there can ever be an objective view on how likely (probabilistically) he is to act different ways.

Differing Values

Another challenge in reaching consensus is that everyone has beliefs and values that they largely take for granted, that they perhaps cling to more strongly than others people do.  

Maintaining beliefs of this kind is natural, and I would even say helpful, particularly when faced with complex situations which don’t have clear cut answers, for example when considering political and social questions.  It is a lot easier to follow instinctive rules and habits (eg be nice, follow the rules) than to work out every question from first principles.

While it is possible for us to have fundamentally different values, in practice I find these cases rare, at least with the people I talk to.  Far more common in my experience is when we both share values, but prioritise them differently.  For example, the vast majority of people I know want to prevent harm, deter cheaters, improve outcomes, allow freedom - but how they weigh these up against each other, and which they are willing to question, still allows huge room for argument.

The challenge is to make the effort to understand what the other party values (noting that we will most likely value it too, even if less strongly), but to highlight the tradeoff.  Sometimes this will resolve the question - our friend might recognise that their instinct leads to a worse outcome.  But even if it doesn’t resolve the question - for example if the other party is happy with a tradeoff that I’m not comfortable with, at least we’d have a better understanding of where our disagreement is really coming from (rather than an assumption that the other person is evil!).   


To conclude, I certainly don’t want to discourage my friends from their convictions, nor to deter them from standing up for what they believe is right.  But I hope that by occasionally taking a step back, and realising things aren’t as absolute as we tend to think, they might be more effective at bridging the divide, and ultimately convincing people