大家参加A-level考试，不少同学选择参加考试科目的时候，会选择物理课程，但是物理课程并不是很简单，需要大家用心用脑，那么备考A-level物理考试，有什么好的方法吗？今天小编就来说说ALevel物理中实证表述和规范表述的知识点！
实证表述：企图描述世界是什么的观点。
规范表述：企图描述世界应该如何运行的观点。
1、实证表述 Positive Statements
Positive statements are objective statements that can be tested or rejected by referring to the available evidence.positive statements are claims that attempt to describe the world as it is.Positive economics deals with objective explanation and the testing and rejection of theories.
例如：
A rise in consumer incomes will lead to a rise in the demand for new cars.
A fall in the exchange rate will lead to an increase in exports overseas.
More competition in markets can lead to lower prices for consumers.
If the government raises the tax on beer, this will lead to a fall in profits of the brewers.
A reduction in income tax will improve the incentives of the unemployed to search for work.
A rise in average temperatures will increase the demand for chicken.
Poverty in the UK has increased because of the fast growth of executive pay.
2、规范表述 Normative Statements
Normative statements express an opinion about what ought to be. They are subjective statements rather than objective statements – i.e. they carry value judgments.
例如：
The level of duty on petrol is too unfair and unfairly penalizes motorists.
The London congestion charge for drivers of petrol-guzzling cars should increase to ￡25 - three times the current charge.
The government should increase the national minimum wage to ￡6 per hour in order to reduce relative poverty.
The government is right to introduce a ban on smoking in public places.
The retirement age should be raised to 75 to combat the effects of our ageing population.
The government ought to provide financial subsidies to companies manufacturing and developing wind farm technology.
这两种表述的关键区别在于我们如何来判断其有效性（validity）。
原则上，实证表述是可以通过对证据的检验来肯定或是否定的；而规范表述除了事实，还包括价值，判断一项政策是好是坏不仅仅看科学事实，还包含我们对伦理道德，宗教信仰，以及政治哲学的看法。
当然这两者也是互相关联的，实证分析会对规范分析产生影响，但规范分析结论不仅需要实证分析，还需要价值判断（Value judgement）。
下面来看一个例题：
What must be true of a positive statement?
A It is one that can be shown to be correct or incorrect.
B It is one that deals with positive changes in economic well being.
C It is one that is true by definition.
D It is one with which everyone is in agreement.
答案：A
首先从定义来看，positive statements are claims that attempt to describe the world as it is.实证表述是企图描述世界是什么的观点，换言之是对事实的一种客观描述。既然是事实，我们就可以判断它的对错，与选项A相符。这里容易勿选成D，要注意的是，三人成虎，并非所有人都同意的就一定正确，可能由于人类认识的发展局限性而造成所有人都错误的结果。而选项C中，定义表现的是所下定义的人的思想认识，也就是我们说的涉及个人的value judgement，因此不能判断为positive statement。
以上就是小编为大家带来的ALevel物理中实证表述和规范表述的知识点，提高备考能力，不要忽略基础的提升，并且大家一定要重视真题的训练，如果还想了解更多alevel作文范文、考alevel多少钱等更多信息，大家可以在线咨询客服！
