Principles of Economic Reasoning: How Are Expected Costs and Benefits Distinct from Ethical and Moral Judgments? This question relates to principles of economic reasoning in a non-financial context:
How are economic principles applied to non-financial models, such as a democratic election?
One may reverse the assumption and ask how benefits and costs in a financial context would be evaluated without recourse to making ethical and moral judgments?
For brevity one may describe an ethical philosopher as a person who makes an effort to answer two questions:

What is good?
How should one act to cause the good?

Terse principles of economic reasoning might be stated as follows:

Maximum benefits are good.
One should act to maximize benefits and minimize costs in the social context.

Public good would be an effort to maximize benefits and minimize costs for a group of individuals. Private good would be an effort to maximize benefits and minimize costs for each individual while interacting with members of the social group. Edit: Pareto efficient outcomes occur when no one is worse off.
How then is economic reasoning distinct from more general efforts to determine what is good and how one should act to cause the good? If people demand government solutions to social problems and economists debate the costs and benefits of different types of government institutions then is this not a political, ethical, and moral debate which cannot be resolved via recourse to an independent economic reasoning skill?
The following is simply not accurate statement about economics:

Terse principles of economic reasoning might be stated as follows:

Maximum benefits are good.
One should act to maximize benefits and minimize costs in the social context.


In order to answer this question, and see why the statement is inaccurate, it is important to recognize that inquiry in economics (an other sciences as well), can be split into two categories:
Positive Economics: Positive economics deals with questions of what is. For example, what is the elasticity of demand for market for potatoes? What is the effect of rising minimum wage on employment? etc. (see Mankiw Principles of Economics pp 27.). Most economics as practiced today (in academic research) is positive economics.
Normative Economics: Normative economics deals with question what ought to be? If we estimated a differences-in-differences model that shows small increases in minimum wage do not significantly affect employment should we increase it or not? (ibid. Principles of Economics). Normative economics is mostly dealt with in public economics or in practical public policy.
Now it is plain to see that positive economics and research about positive economics simply does not concern itself with maximum benefit or whether one acts to maximize benefits and minimize costs (from moral perspective that is).   When we model rational behavior of profit seeking firm  in positive inquiry we are not implying that firm should act that way - we are attempting to just be descriptive and describe the behavior of firm.  When we say people are trying to maximize their utility (or when behavioral economists tell us sometimes they don't) we are not claiming this is moral thing to do or they should behave in such way. This is done without any moral judgement or prejudice similar way as physicist would describe motion of a gas or planets (of course, the precise techniques will differ but in principle on fundamental level there is not much difference).
Hence already from onset we can safely say that whole corpus of positive economics is  distinct from making any moral or ethical judgements so let us turn our attention to normative economics.
Normative economics deals with ethical and moral issues but not by any means in such overtly reductionist way as suggested in the 'terse principles' you stated.
Normative economics will nowadays start with recognition that although economics originated in moral philosophy* it is no longer part of it and we economists are not anymore specialist in moral philosophy (of course, a person can have multiple specializations one can be both economist and moral philosopher the same way as one can be biologist and moral philosopher, or as someone who can be both physicist and chemist at the same time). Consequently, when we make normative inquiry we won't start by trying to deduce what is moral or not from first principles.
Rather in normative economics we start by looking at past work of moral philosophers and moral frameworks that are already developed (yes sometimes those moral philosophers happened to also be economists - e.g. Adam Smith - theory of moral sentiments, Amartya Sen - Capability and Well-Being etc.). The three widely popular moral frameworks used across public econ literature are moral philosophies based on Rawls' theory of justice, classical liberalism and utilitarianism but there are of course many more different frameworks used (see Ross (2014) Philosophy of Economics for short overview).
In both Rawls theory of justice or classical liberalism the objective is neither to maximize benefits or minimize costs in either private or social context (see Rawls (1971)
A Theory of Justice; Nozik  (1974)  Anarchy, State, and Utopia). Rather a Rawlsian economist would recommend to conduct economic policy in accordance with maxmin principle i.e. maximize welfare of the poorest member of society and nobody else (although once you raise one person someone else becomes the poorest so Rawls is not implying to take care of only one person). A classical liberal/libertarian economist would favor any policy that minimizes the use of force and coercion by state (even if it would not necessary maximize utility - classical liberals are not utilitarians). Utiliterians would indeed want to maximize benefits and minimize cost in terms of utility.
However, note in athe above cases it is not really the economist who postulates what is good or bad. Rather the economist will defer to moral philosophers. Furthermore, when doing normative economics an economist will not necessary even pick a side. Vast majority of the corpus of public economics literature usually makes comparative analysis that takes into account several different moral  philosophies. For example, in optimum income taxation literature people routinely estimate optimal taxes and transfers using Rawlsian, utilitarian, classical liberal (also known as conservative - due to US politics where conservatives tend to be economically libertarian) or other welfare function (see Saez 2001 as an example of a study that does this).
Of course, ultimately in a democracy it will be people to decide which social welfare function society adopts, and people should decide based on their own values and moral principles. I think most economists nowadays humbly acknowledge this.
This being said economists are also people and most people love discussing politics and moral philosophy so many economists will frequently make statements that go way beyond even normative economics. Some will even dabble in moral philosophy more professionally. This is not unique to economics. You will find many physicists such as Einstein for example who at some point started to dabble in moral philosophy. While in case of physics it can be easy for people to make distinction in economics this can be more difficult due to the historical roots in moral philosophy that economics has but that does not make 'principles of economic reasoning' any more close  to it.

* I am specifically putting emphasis on 'moral' as it can be argued no science can be divorced from metaphysics and other branches of philosophy that deal with epistemological questions (see Ross cited above).  How do we even know we can know anything? Is there even such thing as a 'fact' or 'objective truth'?