Picking the Right Level of Analogy
Analogies can be powerful but risk being misleading if the level of abstraction is chosen too high, inadvertently including unwanted comparisons. The key is to make explicit the underlying principle (X) that justifies the analogy and to check whether moving up one level necessarily forces acceptance of higher, more extreme levels.
THE IDEA
PICKING THE RIGHT LEVEL OF ANALOGY
My wise friend Gregory Peebles says analogies are like bridges that can take us anywhere – so we’d better be careful what bridge we choose. Indeed, if we pick a high level of abstraction we’ll encompass practically everything as analogous, which could include things we didn’t want at all. This is how using analogies can sometimes go wrong and cause worse arguments rather than better ones.
Using an analogy in a discussion usually goes like this. You’re trying to argue or explain a statement A. You draw an analogy to a statement B that is more engaging, accessible, or clear cut. Implicitly there is a principle X at work. The claim is:
A is analogous to B. B is true. Therefore A is true.
This is much less watertight than using an actual logical equivalence:
A is logically equivalent to B. B is true. Therefore A is true.
The reason is that the analogy must go via some implicit principle X. The unspoken part of what is going on is:
A is true because of principle X. B is also true because of principle X. B is true. Therefore A is true.
There is now a logical flaw in the argument, which is that just because B is true it doesn’t mean that principle X is true. The truth of B does not establish the principle that would justify extending the analogy to A.
This is made worse by the fact that in normal arguments in life we often don’t state what principle X is at all: we just leave people to infer it from statement B. This is very flawed because there are many possible principles that could play the role of X and they could give us very different results.
For example, supporters of same-sex marriage say that a same-sex relationship is no different from a heterosexual one so same-sex couples should be allowed to get married. The excerpt does not supply the precise general principle intended to include both heterosexual and homosexual relationships. Those opposed sometimes claim that if we allow same-sex marriage, then “the next thing we know we’ll be allowing incest”. They are erroneously (or wilfully) supposing this level of abstraction is at play. The disagreement is in the principle X. Those opposed want the principle only to go as far as “unrelated man and woman” so that straight marriage is not analogous to gay marriage. In seeing someone adopt a higher level of abstraction their imagination or fear sends them escalating much further than the other person has really gone. In fact, there’s a big hierarchy of increasingly wild arguments. Some people think allowing gay marriage will encompass paedophilia or bestiality. The discussion refers to a hierarchy diagram, which is not included here. Its point is that broader principles can include more cases. The fact that someone is pro–gay marriage does not mean they have necessarily accepted the principles all the way up to the top. It is worth remembering that there used to be further levels below “an unrelated man and woman”, when marriage was not allowed between white people and non-white people. A more nuanced argument than “the same” vs “not the same” would be to think about which level of abstraction is justifiable. Claiming that going up one level necessarily involves going up more than one is an erroneous argument.
When to use it
When debating policy changes, to avoid false equivalences or unfounded slippery‑slope arguments.
In teaching critical thinking, to illustrate how analogies can be valid or flawed depending on the chosen abstraction level.
When writing persuasive arguments, to ensure that analogies are not overextended and that the underlying principle is clearly articulated.
In analyzing political or ethical debates, to deconstruct how opponents may intentionally shift the level of abstraction to make a point.
FROM THEORY TO EVERYDAY LIFE
In practice
Same‑sex marriage and the incest analogy
Supporters of same‑sex marriage argue that a same‑sex relationship is analogous to a heterosexual one, so the same principle (e.g., consenting adults should be allowed to marry) justifies both. Opponents counter with a slippery slope: if that principle is accepted, then incest, paedophilia, or bestiality would also have to be allowed. The error is that the opponent implicitly raises the level of abstraction (e.g., from ‘consenting adults’ to ‘any kind of sexual relationship’) without showing that the supporter actually endorses that higher principle.
A MOMENT TO REFLECT
Put it to work.
Think of a recent argument where an analogy was used. What was the implicit principle X? Was it justified?
Can you identify a case where someone accused another of a slippery slope without checking the actual level of abstraction being used?
How can you make an analogy more rigorous by explicitly stating the principle it relies on?
CONTINUE THE CONVERSATION
Source texts
- The Art of Logic How to Make Sense in a World that Doesn’t (Eugenia Cheng)