> when designing a software that helps users design things, what are the design principles that help expand the possible range of human thought?

The thing that computers do well is detailed simulation of possible configurations and visualization of aggregate results. The single best, most inspiring thing a computer can present is an entirely unthought of arrangement, i.e. a surprise.

Humans are routinely surprised by computers, but what software is principally designed to surprise its user?

The part of the speculative realist movement in philosophy which overlaps with software developers (which is relatively large) has put quite a lot of effort into such surprising software. https://10print.org/ is probably the most publicly-accessible reach of this. (Some parts of this movement also stand in direct opposition to the anthropic view the article takes, but there's also a lot of overlap.)

Unfortunately this is insignificant compared to the explicitly anti-speculative reductionist mode most software developers operate it.

I like modularity and compositionality for things like this, like Lego, that let you try how ideas fit. Some examples are Jupyter notebooks, Matlab, Simulink etc