Psychology shifted away from pure theory and towards more careful and systematic empirical observation.

心学从纯研究转向了更加细致系统化实证观察。

But all our talk was limited to pure theory and nothing else.

但我们讨仅限于纯，没有其他内容。

These purely theoretical concepts led the way to  atomic theory and the unfulfilled biology field.

这些纯概念引领了原子未实现生物学领域。

But many participants in The Republic of Letters were focused on less theoretical matters.

然而，“书共国”中许多参与者更关实际而非纯问题。

This is a question for historical generalisation rather than for pure theory.

这历史概括问题，而不纯问题。

In the case of purely theoretical books, the criteria for agreement or disagreement relate to the truth of what is being said.

对于纯书籍，同意或不同意标准与所讲内容真实性有关。

I don't think that was wrong, you know, back months ago, to highlight in pure theory, a one-time tariff is a one-time increase in cost.

我认为几个月前从纯角度强调一次性关税一次性成本增加并没有错。

Why did they satisfy themselves with the meager theory of positive external effects as a corollary of the equally pitiable theory of pure and perfect competition?

为何他们满足于将正外部效应这一贫乏作为同样可悲纯完全竞争附属品呢？

In the other kind of practical books, the kind dealing mainly with the principles underlying rules, the major propositions and arguments will, of course, look exactly like those in a purely theoretical book.

在另一类实用书籍中，主要涉及规则背后原、主要命题证书籍，当然看起来与纯书籍中完全相同。