Economics is not politics by definition. Whether economics is science depends on what view on demarcation of science you adopt but most of the economics will pass virtually any commonly used criteria in philosophy of science and there is no doubt it passes the mainstream demarcations such as the Popperian one.
The most common definition of economics comes from Lionel Robbins (1935, p. 16):
“the science which studies human behavior as a relationship between ends and scarce means which have alternative uses”
Economics can be further split into two main branches (see Mankiw Principles of Economics, pp 27):
- positive economics: Positive economics describes how things are. It describes mechanisms and relationships and scientific laws.
For example, positive economic statement is: "Nominal GDP of the Netherlands in 2020 is \$886 billion" or "there is positive relationship between inflation and output in the short-run", or "labor supply elasticity with respect to income tax is -0.2".
Positive statements can still be right or wrong but this is judged based on empirical evidence. These are analogous to statements from physics like, "sun is center of solar system", "Milky Way galaxy has spiral shape".
If there is any disagreement on matters of positive economics it is only to the extent we are unable to measure something precisely.
For a well known analogy from physics; there used to be disagreement in physics about nature of solar system (e.g. heliocentrism vs geocentrism) but the disagreement was not political it was created by the fact that we were not able to measure position of Earth and movement of planets and Sun and Moon accurately enough to determine which of the two models is wrong.
Economics, in same way as physics or biology applies scientific method to test positive statements.
- normative economics : Which actually asks questions of what ought to be? But these questions are based on pre-existing philosophies and seeing what conclusions one can apply for them given results from positive economics.
For example, according to Rawlsian ethics public policy should aim for max-min principle. That is according to Rawlsian ethics public policy should maximizing the wellfare of the poorest members of society.
Based on the above max-min criterion one can derive the optimal tax schedule that should be applied to income of each individual. That optimal tax schedule derivation can be checked and it can be tested by experimentation in real life and so on.
Examples of normative economics statements thus are: "If you adopt utilitarian social welfare function the optimal top marginal tax rate ought to be 70%" or "If you adopt charitable conservative social welfare function optimal top marginal tax rate ought to be 80%," or "if you want to reduce CO2 emissions by $x$ metric tons there ought to be $y\%$ carbon tax".
Normative economics does not question ideology/beliefs it takes them as given. An analogue to policy economist doing normative economics research is engineer building a bridge. Someone has to make decision to order that bridge should be built. That decision might be politically motivated communist party might demand bridge to be constructed 'for the people' businessman might order construction of bridges for their trucks, senator might want to build bridge to please their constituency. Engineer just tells you how much cement will you need, how wide the bridge needs to be for stability, how it needs to be assembled so it does not break.
How is the above science?
What is and isn't science is the famous demarcation problem from the field of philosophy. Economics.SE is not place for Philosophy Q/A, so I will treat this part only very briefly. There are various views on demarcation of science, economics would be categorized as a science under most of them (but not all, but that holds for any field even physics).
Discussion of all views on demarcation of science would be beyond scope of Economics.SE so I will focus on the mainstream Popperian view of demarcation of science (but as mentioned Economics would clear virtually all established views for more info on that have look at Ross Philosophy of Economics, or Hausman Philosophy of Economics: An Anthology).
Under the Popperian view what you are doing is science if it is falsifiable. According to Popper statements or systems of statements can be scientific only if they can possibly be disproven by empirical verification.
"labor supply elasticity with respect to income tax is -0.2" is science/scientific statement because the statement could be disproven by evidence which would show that labor supply elasticity with respect to income tax is not -0.2.
"if you want to reduce CO2 emissions by $x$ metric tons there ought to be $y\%$ carbon tax" - is a scientific statement because we could find by empirical observation that $y%$ carbon tax does not yield reduction of emissions by $x$ metric tons.
"Take from the rich and give to the poor" - is not a science. No amount of empirical observation can disprove statement: "Take from the rich and give to the poor". You can make infinite number of experiments, have god like omniscience and be aware of all facts, but nothing can show that statement is false. That statements is unfalsiable. It is expression of value/ideology/political view but not science.
"Take from none, and allow the Invisible Hand to decide the winners and losers," is again not science. No amount of empirical observation can falsify that statement. Even if there would be crystal clear evidence that laissez faire improves all aspects of life or that it leads to poverty or ruin cannot disprove that statement.
"we should increase taxes by 10%" - is not science as nothing again can refute that statement. No matter of empirical observation on disadvantages of taxation or on other hand benefit of public spending funded by taxation can ever disprove that statement.
"people should not smoke" - again expression of value not scientific statement
"smoking causes cancer" - this would be in the domain of science (although not economics in this case but I wanted to throw one more down to earth example).
Has many definitions in literature, for example David Easton who is very renown political scientist defines in his book the Political System, an Inquiry Into the State of Political Science politics as:
the authoritative allocation of values for a society.
different political scientists might offer different definition because the term is broad, but:
- None of the definitions I ever heard overlaps with definition of economics.
- In your post you make clear that what you mean by politics are political statements like: "Take from the rich and give to the poor" which are rather statements of value, ideology or ethics.
Economics is a science under widely used demarcation criteria of science and it is quite distinct from politics.
This does not mean that there are no economists who are also interested in politics, or that there are unprofessional economists who will not make clear when they are talking about science and when they are professing their ideology. In every field there are malpractitioners. Additionally, even the best economists might occasionally slip up the same way as even the best surgeon can make a mistake during surgery.
Lastly, politicians like to create conflicts because conflicts are the heart of politics. According to the Oxford Handbook of Political Ideologies by Freeden et al:
Politics—in democratic societies—is based on general agreement on certain key concepts
like democracy, freedom, solidarity, welfare, progress, etc., but on deep
disagreement when it comes to giving substance and content to these concepts.
Politics is thus based on both agreement and disagreement. Without agreement
there is no political cohesion and framing of the political process but only
fragmentation. Without disagreement there is no politics (Koselleck 1979, 1988
). Without disagreement there is only administration of consensus. Politics
in democratic societies is not about consensus but about conflict and the search
for compromises, for positions of compatibility of the incompatible.
Politicians will routinely create conflicts in society even about established facts/science (e.g. climate, age of Earth, Evolution etc ). These conflicts are at their core often unscientific, they are either conflict of values or if not conflict of values than just opposition to what other side of the aisle is saying just for sake of opposition since without disagreement there cannot be any politics. These conflicts will virtually never have anything to do with science whatsoever, but without doubt many unscrupulous politicians will often (mis)cite science in order to appear more authoritative and fool people into thinking that is relevant for their squabbles about value judgements. In reality it is not, value judgements cannot be refuted one can only show they are consistent with one or other system of ethics and one might try to persuade opponent to tweak their ethical system but there is no science that can falsify or provide credence to any ethical proposition whatsoever.