How to scientifically answer questions like wear a mask or not?  Anyone and everyone can think scientifically.  It is thinking systematically and critically about the information and considering the ethics of your choice given that information. It is also being open to new information which can change your mind. The key is knowing that public science is a process of independently assessing information gleaned from reliable sources.  The hard part is being open to that information even if it goes against our own biases or preferences. Lastly thinking ethically about your choices. Could what you do adversely affect someone else?

What Is Science For Joe Everyman? 

The first thing to know is that science is an exercise in independent critical thinking not rote memorization and regurgitation of facts.  Thanks to a poor education system many people get through high school and even college without ever experiencing inquiry-based science learning.  To do real science for the sake of informed decision-making means thinking critically about the information presented by the professional expert scientist.   To read critically look at the citations for every fact they present.  Ask yourself the following questions. 

Are their citations to formally written scientific papers?  If those papers are very new are, they posted in formal scientific forums and archives?  If those papers are a year or more old are, they published with a DOI with some degree of peer review?  If those papers are more than a year old have, they been cited by anyone else? 

Anyone can engage in a critical thinking process, at some level, to make an informed decision about their health.  Nothing mentioned above requires special training beyond clicking the links that should be at the bottom of any scientific paper.  New articles should link to the scientific paper with full reference information.  They should also, if not written by a scientist, give a quote from the scientist they write about and one from another scientist who has read the paper.    When reading news articles about a hot new scientific topic the best sign that it is professionally written is if it gives you the impression that they are not 100% sure of the findings.

The round Earth being a place where life evolved, where humans can change the climate, which revolves around the Sun, and which formed billions of years after the big bang are not hot new topics.  A publication which denies settled science is not a good place to look for science information. 

The third is that thinking scientifically also means thinking about the whole system not just what is right for you.  This is what we call scientific ethics.    Suppose you feel like you have a strong immune system and that if you get covid-19, aka CCP virus, it will not affect you much.  That is a valid finding for yourself.   Thinking systemically and ethically means considering what could happen to other people you may encounter if they get it.  People who are older or who have compromised or suppressed immune systems could suffer. 

Example: You are a strong guy and never get sick, exercise, and take care of yourself, and are not afraid.

Quite possibly you have a particularly strong immune system which may not be normal or average.  One of the strongest biases can be thinking your own case or experience are the same as everyone else’s. Immune system strength can be influenced by general health, but it can also influence general health.  Often an immune system that is too strong or too active can be a problem (allergies at the mild end or autoimmune disorders at the more serious end of the spectrum.)  Then there are those who are healthy and normal but catch most every virus that comes around.  For them this could be a miserable ordeal even if it does not kill them.

You decide to ask “Should I wear a mask even if I don’t think I will get sick?”   Then you Google and see the information from the WHO which says not to wear a mask unless you are sick.  Then you google to see what the CDC says and they say you should wear a mask if you are in a community setting.   Here we have the World Health Organization contradicting the US Centers for Disease Control.  Who should you listen to?

How not to decide:
The WHO represents the world and is not ran by Trump therefore they are who I will listen to.

The CDC is ran by good Americans and the WHO is influenced by the Chinese Communist Party.

Those are both true and valid ideological points of emotion, politics, geopolitics, and realpolitik.  However, they are scientifically irrelevant to the question you are asking.

How to decide:

Look at each page and consider the sources they cite as well as the context and audience they are for. The WHO website cites white paper published by them.  Such papers by large institutions do not undergo external peer review but are usually reliable.  The white paper itself cites 26 more sources. https://apps.who.int/iris/bitstream/handle/10665/331695/WHO-2019-nCov-IPC_PPE_use-2020.3-eng.pdf 

The CDC website https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover.html  Cites seven studies which say that face mask help.    This website is equivalent to a white paper as like such a paper it gets vetted by the scientist who work for such a large organization.  However, it too has not been externally reviewed.

The tie breaker is using your own critical thinking.  The WHO is writing for a global audience.  That could mean anywhere from big cities to the deep isolated deserts.   The CDC says you do, they are writing for a US American audience taking account of local conditions, namely active community-based transmission.  Think of where you are going is it more like the average world conditions or more of a crowded condition.

Going to jog alone or with one friend on an isolated trail or to work alone in the back yard or to swim at a nearly empty beach likely does not require a mask. 

Going to the grocery store, just after work, when it is going to be crowded, going to a bar to sip a beer (you lower the mask for a sip and put it back up ), going to a memorial day barbque where your grandfather who fought in Vietnam at the battle of An Loc.  Then you need to think about the possibly weaker people around you and wear a mask.

Since conditions could change from crowded to not crowded maybe keeping a mask handy is the best compromise.  You can wear it if you have no choice but to be too close to a large group of people.

The last part of critical thinking is to challenge your own thoughts.  Be your own worst critic.  Question everything.  Maybe you should wear a mask even while jogging in an isolated place since your germs could linger in the area for hours.  Maybe you should not wear a mask at the store since you want to get other to “herd immunity”.   Maybe it is grandfather war hero’s time to go, old people dying is natural?

Then after you have thought critically and challenged your own thoughts it is time to think ethically. 

Between wearing a mask and not wearing one which choice can cause harm to someone else? 

Personally, I wear a mask when out in public places to protect others from any possible infection in my family as well as to give a measure of protection to my family.    I do not wear a mask in the backyard or in the car driving to a public place.

The same holds for medicines.

Consider people who wish to ask their doctor to put them on Hydroxychloroquine.  One can find papers that say it is poison.  One can find papers that say it is preventative.   The way to think critically about those papers is to consider the sample sizes.  A study of 1000 people is more significant than a study of 100.  Then there is the ethical consideration can take this medication harm anyone else but me?

In summary

Make a sound decision on mask wearing and the many experimental drugs. Think critically, think systemically, think ethically.  Those three things are the bedrock of thinking scientifically.  Don’t wear a mask because authorities say so, don’t refuse a mask because an authority figure does not.  Make your own real choices.   Consider the conditions you are going into if you are sick but asymptomatic will you make a couple dozen other people sick?