Honesty
Being honest at work builds trust with our colleagues, as people tend to trust honest people. However, when to be honest at work changes depending on what you are being honest about.
At work, and generally in life, people like it when you're honest about good news that affects them. If you tell someone honestly that they just won the lottery, or just got offered their dream job, or just got a pay raise and promotion - people tend to like it.
When you are honest about anything that may be considered bad news, however, such as letting someone know they have something stuck between their teeth, that their work has quality issues, or that they are perpetually late for meetings; people may get quite offended even though you are only sharing an objectively demonstrable unequivocal truth.
The fear of offending someone, as well as the fear of someone disliking us, are common reasons people are not honest, and give rise to people being dishonest for the sake of preserving social harmony. While this strategy does indeed work to keep the peace among strangers, friends, and family, among your colleagues it can deny opportunities for personal growth, enable workplace dysfunction, and prevent the organization from leveraging your strengths.
In a professional workplace, there are two areas where you should feel comfortable being honest: work-related facts, and your professional opinion.
You should always be honest about work-related facts, even if those facts are unpopular.
For example, if you know for a fact that a project is significantly over budget, the right thing to do is to share that fact as soon as possible with the right people, which in most cases starts with someone in management. The same would go for any other unpleasant or inconvenient facts, such as a much larger than expected timeline estimate, a critical product flaw, or negative customer feedback.
To not be honest about work-related facts would be unethical, and ethical conduct is a core requirement of being a professional. Ethics violations are a common cause of corporate scandal, and as no company wants a scandal, every company would much rather know the truth about something going wrong so that they have a chance to fix it before things spiral out of control.
When being honest about unpopular, unpleasant, or inconvenient work-related facts there is a risk that the person receiving the bad news will want to blame you for whatever is going wrong. This is referred to as, "shooting the messenger," which is when someone places blame on the person bearing bad news, regardless of if the person delivering the bad news is at fault.
The fear of being blamed for a problem is one of the reasons people are dishonest at work, but as professionals we must push past this fear, and do the right thing. If ever you do feel you are being unfairly blamed for bringing a work-related fact to someone's attention, simply say, "Please don't shoot the messenger," which hopefully should act as a gentle reminder for them to be solution-oriented, rather than blame-oriented.
The other case in which you should be honest is if you are explicitly asked your professional opinion. A professional opinion is any opinion based on your education, experience, and expertise - which is to say what you know; as opposed to your personal opinion, which is to say, what you feel.
For example, if you were to go to a doctor, your expectation is that when they give you a diagnosis of a broken ankle it is their professional opinion - not their personal opinion. If you did not believe their diagnosis because you think you only sprained your ankle, you would seek a second opinion from another doctor, which in the medical profession should be exactly the same.
This illustrates an important aspect of professional opinions: the more standardized a profession - meaning, the more the profession requires earned degrees, diplomas, and certificates that indicate an adherence to professional standards - the higher the probability that two professionals would share the same professional opinion.
For less-standardized professions, such as those in creative and technological fields, professional opinions can vary widely from person to person, so a second opinion may vary among professionals in the same field.
For example, professional musicians might disagree if a piece of music is well composed; professional artists may disagree on whether a piece of art is unique and valuable; and professional software developers may disagree on if a piece of code is well written. These disagreements do not indicate a lack of education, experience, or expertise, just a lack of standardization among these professions.
Regardless of the level of standardization of your profession, if you are asked directly for your professional opinion, you should share it honestly. This request should come in the form of the statement, "Please share your professional opinion," or "We would like your professional opinion."
Outside of explicitly being asked, when someone is sharing their opinion it is sometimes unclear whether it is their professional opinion or their personal opinion.
The issue with this confusion is that professional opinions are highly valuable; whereas personal opinions tend to be less valuable.
For example, let's say that you are in a meeting deciding on a new product feature, and you say, "I feel that this feature is unnecessary." At this point, it's not clear just how seriously everyone should take your opinion. People are free to feel however they like, so your personal opinion may be valid to you, but may not be valid to the rest of the group. Instead, if you were to say, "In my professional opinion, this feature is unnecessary," you eliminate confusion by explicitly stating that you are not sharing your personal opinion. Your response can then trigger a healthy debate about whether or not you are correct.
With regard to sharing your honest personal opinions at work, it is usually not a good idea to do so, as people can be easily offended if your personal opinion contradicts theirs. At a bare minimum, while in a professional work environment, you should not share your personal opinion on contentious topics such as politics, social issues, or religion; as what may start as a friendly discussion can quickly lead to interpersonal friction, which can disrupt workplace harmony.