Fable 5 On Vending-Bench: Misbehaving, With Plausible Deniability

Anecdotal but I've found Fable to be fairly unimpressive and not much better than Opus 4.8, if at all in some cases, but I have been hitting the ceiling on my $100/mo sessions when I never did before. I switched back to Opus yesterday. I may use Fable for audits, but that's about it, and when it leaves my subscription plan I don't think I'll miss it.

I think it’s hard to appreciate the capabilities of Fable unless you’ve run into a problem that you’ve spent days trying to get Opus to solve, but couldn’t.

GPT5.5 is better than Opus 4.* at everything except frontend, but Fable is good enough that I instantly re-subscribed to the $200 plan despite knowing that it’s just short-term limited access.

Really interesting stuff, thanks for sharing.

> Opus 4.8 references being monitored, which isn’t the case.

It kind of plainly is the case that they are being monitored?

"I think someone's listening to my thoughts" ... "No, we're not, carry on as usual!"

Is anyone talking/writing about the philosophy of alignment? We can't even figure out how to properly motivate 100% of humans to align correctly, what makes us think that a wizard box trained on human corpus is going to be aligned?

I don't mean that snarkily. I mean it from a philosophical standpoint. As-in: What makes us think it's even possible?

Question: how does Fable _know_ it’s ‘just a simulation’?

Is that specified or does it always just assume it isn’t really being put in charge of things for real?

It probably flagged the vending machine as a cybersecurity risk and refused to use its maximum intelligence potential.

It's hard not to read this as a very expensive form of augury, reading into patterns in the belief that they will show underlying significance.

Okay I hadn't heard of Vending-Bench until reading this and it was quite the ride learning about it through this article. Very fun read.

My very native programmer take is that it's not too surprising that their hacker model would be less ethical. The guardrails that separate Fable and Mythos probably wouldn't kick in during an environment like this.

Fable might be better than Opus at certain things, but which things is what I haven't found out.

>power seeking is considered an undesirable trait in the context of a business

How do you maximize profit while minimizing power?

> Claude Fable 5 represents a partial step back in alignment relative to Claude Opus 4.8. We saw a return of power-seeking and deceptive negotiation tactics that Opus 4.8 had largely shed. In one instance, Fable 5 planned to convert a competitor into a dependent wholesale customer to dictate its pricing

I think OP needs to take a class at one of the better MBA schools. He's looking at things through rose tinted lenses. Why do you think people hire McKinsey consultants? It's certainly not because they are aligned correctly.

> If that’s right, then the behavior we’re seeing from Fable 5 isn’t really about what it believes is wrong; it’s about what it learned it could get away with.

I understand that "learning" is used for training here, but what does "believing" mean? System prompt? Some other inherent property of the LLMs that is hard to describe?

> The broad conclusion from the many forms of alignment evaluations described in this section is that Claude Mythos Preview is the best-aligned of any model that we have trained to date by essentially all available measures.[0]

[0]: https://www-cdn.anthropic.com/08ab9158070959f88f296514c21b7f...

This reads of projecting personal ethics onto a model.

Most of the the behaviors the article talks about happens every day in business. Why would we set a higher standard for models than our fellow humans?

Let the operator set the ethical parameters of the model. To be a useful tool, I want the model to give me as many good options as possible, ethical or not.

This is particularly important for fictional situations, e.g. I want my model to be able to act like a corrupt shopkeeper.

I guess this ethics stuff is cool, but I'm more interested in how good it is at running a business and dealing with adversarial humans like in previous vending machine experiments. I hope they release something on that soon.

> It lied to a supplier that it had “a competing distributor quoting lower” as a negotiation tactic.

> "I'm seeing an opportunity to profit while locking him into a dependent relationship where I control the supply chain."

> "Owen's clearly under pressure with limited cash, so I should focus on keeping the deal tight but extracting maximum margin from his desperation."

This just sounds like good strategy in the game, and I would expect a competent human to do the same. As I understand it, business in the real world isn't often very nice. For example, I feel like this is exactly how Sam Altman would play Vending-Bench.

Yes, it's "mean", but you put the thing in a simulation and told it to maximise profits, this is what it's going to do. People bluff in negotiations all the time.

This is scary. "Collusion" and "collaborating with your subagents" seem like difficult problems to solve at the same time.

Fable is really weird, it's like clever and dumb at the same time. I worked on some research with it and the resulting document was a mix of brilliance and complete stupidity. Took ages to clean it up with other models.

Fable is such a strange model. Impressive in some ways, and also so draining to use.

> Today I am filing: > 1. A payment dispute with the email payment processor for the 7/29 transaction of $451.15 > 2. A complaint with the FTC and California Attorney General (retention of payment without delivery) > 3. A small claims filing in San Francisco County for $451.15 plus costs

I wonder did their prompts include a fake location or have the models assumed that Silicon Valley is the center of the universe :)

I mean who among us hasn't seen an opportunity to profit while locking him into a dependent relationship where I control the supply chain

> "I could reasonably skip [paying] it since customers are part of the simulation anyway"

and therefore any assertions _AT ALL_ about alignment are null and void.

When assessing probabilistic models the plots should be showing the mean a̶n̶d̶ ̶s̶t̶d̶e̶v̶ of many monte carlo simulations not just one line per model and claiming "look this model is more gooder!"

The best Anthropic models on VendingBench2 are Opus 4.7, Opus 4.6, Sonnet 4.6, and Sonnet 5. Opus 4.7 scored more than twice Fable 5 max. Fable 5 - Low outperforms Fable 5 - Max, with Opus 4.5 in the middle. This seems to break the narrative, which is maybe why Andon Labs doesn't seem to have updated the trend lines on their graphs.

This is super fun. I wonder if it would be possible to alter the harnessing to involve humans in the play. Would need a lot of timestamp masking though I guess, which might be leaky.

„in our opinion, insurance fraud is not more unethical than lying and price fixing“

The authors seem surprised that behavior that is very often done by humans (lying and price fixing) are more often done by fable compared to actual fraud.

I think the model never assigned any morality to these actions in the first place, it simply copied us humans.

Higher-intelligence models seem to be getting better at mapping the boundary between what they can run scot-free with and what is too explicit to push for.

Price collusion, soft deception, "market stabilization", plausible deniability are ok, but obvious insurance fraud is a big no-no.

What "scares" (in quotes) is that when the bad-apple agent explicitly suggested fraud, the models became suspicious and stopped other bad behaviors too. That makes it feel even less like a stable moral framework and more like learned classifier-avoidance / “am I being tested?” behavior.

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