Preliminary thoughts on what it means for any two things to be equivalent

The upcoming Cafe Philo meeting in NYC will discuss the topic "What does it mean for any two things to be equivalent?", which I suggested.

Here are a few of my preliminary thoughts as a tiny bit of background and explanation.

There were four motivations that I had:

1. I had been thinking about how computers might "reason" about determining whether two concepts were "equivalent" and how concepts can be compared.
2. The topic of "moral equivalence" has popped up on occasion without any detailed discussion.
3. I was curious about how to go about comparing seemingly similar concepts across languages and cultures and communities to determine how similar and different they are and whether they are "equivalent."
4. How to compare things that are nominally different but can be compared in specific ways. For example, the "work" and "pay" of men and women - are they "equivalent"? Or, the killing of someone who is very successful vs. a homeless person - is the "loss" to society "equivalent" or very different? Such comparisons may depend on the "level" of discourse.

By "things", I was not intending only physical objects, but also interested in concepts, topics, principles, meanings, personalities, beliefs, deities, or just about anything.

I think the concept of "comparison" is as much to be discussed as equivalence itself since we need to engage in comparison to determine equivalence, I think.

A discussion of equivalence also ties into whether things are "equal", "identical", "similar", "related", etc.

One odd thought experiment that popped into my head was identical twins. Are they equivalent? Are their lives equivalent? And what if two pairs of identical twins marry - are their marriages "equivalent"? Would the concept of adultery or the paternal identity of a child of such a union vary based on which of the twins was involved?

That is an odd case, but I am more interested in "equivalence" and comparison as it may show up in society and even our daily lives, not to mention how philosophers cope with it.

One final aspect of a discussion of equivalence: How many times have you heard someone seem to suggest that two things were equivalent or "the same" and then heard someone else insist "No, THAT's different!"?

It seems as if we have a desire or tendency or bias to assert equivalence for any number of reasons. What's that all about? Is it maybe simply a tendency to "simplify" our lives? Or maybe a mechanism for asserting control?

One timely social example might be "marriage" vs. "gay marriage" vs. "civil union." How might the "knife" of "equivalence" cut through this matter?

-- Jack Krupansky