[Tainnor]

I'm not sure if that's true, even big effects can be hard to verify if there are significant confounders.

For example, let's imagine that writing OCaml code really leads to fewer bugs than writing code in Lisp (to just choose two languages) but only after you've trained people in OCaml for ten years. Or maybe, technically Java leads to measurably fewer bugs than Ruby, but because most popular Java projects make heavy use of reflection, the effect dissipates... and so on (these are just examples for potential confounders, I'm not claiming they're true).

You are correct that one cannot claim that "static typing leads to fewer bugs" is a demonstrably correct statement, but I don't think you can claim that there demonstrably can be no (big) effect either. And in the end, you're also allowed to believe in conjectures even when there is no solid evidence behind it. People do that all the time, even scientists.

[pron]

You can believe in such a conjectures, but it's wise to consider the more probable possiblity that if an effect hasn't been found, then it is likely small.

Also, in the end it doesn't really matter, because the conjecture that's repeated as an assertion isn't said merely as a scientific claim, but as an attempt to convince. Companies are interested in some bottom line effect, and rather than trying to sell your favourite approach with something like, "I like it; maybe you'll like it, too", you make some unsupported assertion that goes like this: "you should use my thing because it will actually make an important contribution to some bottom-line effect you're interested in; oh, and by the way, you might not notice it." That isn't convincing at all, so it's best to stick with what we know: "I like it, maybe you'll like it, too."

[Tainnor]

Show me the companies that only ever implement policies that have shown to be effective in rigorous empirical studies.

Usually some person (or a group of people) is in charge of some decision and that person will make judgment calls based on their beliefs. This is no less true of programming techniques than it is of management styles, corporate strategy or anything else.

Your insistence that we may not have beliefs about the very things we work with daily, unless they're empirically verified, is IMHO frankly ridiculous.

[pron]

That's not my insistence at all. You can believe what you like. What you can't do is make empirical assertions that we've not been able to validate empirically.

Companies may adopt a technique based on empirical findings or anything else they like; most people choose a favourite programming language because they like working with it better. But the statement that types lead to fewer bugs is a very particular assertion that is simply unsupported by evidence. You may believe that using types reduces baldness and make your choices based on that, but it's still a conjecture/belief at best.

[Tainnor]

I think you're guilty yourself of what you're accusing other people of.

I haven't seen people ITT arguing that there is empirical evidence for types providing better correctness guarantees, just that they strongly believe it to be the case given their own experience.

[pron]

The original statement was "A language with static types would have made it easier to build correct software." This is an empirical claim that the evidence does not support. Note that it's not that there's merely no evidence supporting the claim, but that studies designed to support the claim failed to do so.