When I was in high school, the journalism teacher told us she would accept no excuses. You didn't turn a story in on time, it was on you.
Later, talking to my psychology teacher, he accepted reasons, but not excuses. Reasons, he said, were fact; they may or may not excuse a behavior but they give it context. Context is what you use to measure responsibility and accountability, especially when someone is short of the goals that have been set.
Why do you care when you're reading a blog about management? Because throughout your days you are going to get a lot of reasons, excuses, etc. Whatever they want to call them, people are going to fail to meet expectations, and you're going to have to understand the context in order to determine if they were doing their job or not.
For example: Bob is supposed to finish a task this week that is week that is well within Bob's ability. Bob fails to deliver. Look at the various statements below and think about the context inherent in each (and what other context you might require) and how to respond:
A) Bob had a death in the family
B) Bob got ill
C) Bob got stuck
D) Bob didn't work on that assignment, but a different assignment this week
E) Bob was late to work every day because of traffic issues, and therefore didn't complete because he didn't have as much time to complete the work as expected.
Note there are no "It was Bob's birthday and he blew it off" options; those are relatively clear cut. The above, however, are a list of reasons and excuses. Some will excuse the behavior. Some will not.
The big issue to look at when determining whether something excuses a behavior (or lack of behavior) is whether or not the excuse or reason was within the realm of Bob's control.
Let's look at (A), A) Bob had a death in the family. If Bob had power over life and death, Bob is unlikely to be working for you. (A) is firmly a reason why Bob was unable to complete the work, and, in my mind, a good reason. I don't care if it was Bob's mom, Bob's second cousin twice removed, etc. Some people do care--immediate family only excuses things for them. Some companies even have policies around it. But me, someone dying is beyond Bob's control. Now let's talk a little about context. I can pretty safely say that if someone is near dying or dying or unexpectedly goes, you can't really be expected to plan for that. Death does not invite rationality in most people. Bob, being an awesome person who knew his second cousin was about to go could have told you he wouldn't have that stuff done this week, but even then, excusable in my mind. You never know how death is going to affect you, and it affects you deeply...some people think they can work through it, other people become catatonic (note: I am one of the catatonic folks, it's not pretty).
(A) is the most cut and dried of the available options: you can't control death, and you can't control how you're going to react to death. This means, in my mind, this is an appropriate excuse for the behavior; this isn't going to show up on a monthly report or in the yearly review (other than as "send flowers" or "offer condolences").
Now, a look at (B), B) Bob got ill. This is considerably less cut and dried, if you think about it. You can't control being ill...mostly. Washing your hands, being careful what you touch and eat...generally good things to do, but not something your company can hold you responsible for in terms of getting ill. How ill you are is another thing that can't be controlled. If you and the porcelain god have been making out for days, there's very little that you can do work wise, whereas if you're sneezing every once in a while and really tired, maybe you can work from home.
A brief side note: I am a HUGE fan of working from home, for myself and for others. A lot of people are not so keen on it because they feel if they can't see their employees, its hard to tell if their employees are working. I say PSHAW, sir, pshaw. People produce work daily, and typically have to report it weekly. If they are screwing around when they should be working, they'll miss their deadlines and you'll know not to grant them as much freedom as working from home allows without specific deliverables on the given day.
However, people who feel a little sick are MUCH better to work from home than to come into the office. In the modern day world, contractors and consultants don't get paid if they don't work and full time employees often have paid time off (a pool of vacation and sick days) which effectively has them wondering if the sniffle they are experiencing is worth one fewer day on vacation. Having them come into the office and infecting everyone else is full of suck--now the one or two days they'd be out is multiplied by the number of people they came in contact with, breathed or sneezed on. Thus, I fully recommend having people work from home, if they are able to work.
If they are NOT able to work (see above example of close ties with the toilet), then have them take sick time, or time off without pay, or however it works...if they aren't producing, they aren't working, they can't be paid to work.
That aside, aside, Bob is ill. This could mean that Bob is working from home but getting less done because he's ill, it could be that Bob is taking time off because he's too ill to work. It could also mean Bob is daunted by the work and is taking some sick time to avoid the specific task. Finally, Bob may take sick leave to play hooky for some reason, which means he can't complete his tasks for the week, but it makes it much harder for you to determine if that sick time is excusable for missing the task deliverables.
Obviously if Bob is really ill and really trying, or at least communicates to you about his difficulties, illness easily becomes a reasonable reason that excuses behavior. If Bob doesn't communicate about where he is and what he's doing, and returns talking about the awesome video game that just came out on his sick day when he returns, you might want to look at his overall pattern of behaviors around deliverable dates and that reason becomes an excuse for shirking responsibility. Note: you really need to have your ducks in a row before approaching the concept of people pretending to be ill or being ill too often--check out my last post on Medical and Disability.
Let's look at (C), C) Bob got stuck. Bob was working the problem and couldn't get past certain aspects of it. This is close to cut and dry "excuse" that doesn't actually excuse the behavior. If Bob got stuck and told someone and work with someone to get unstuck and was still stuck, that's excusable. If Bob got stuck and tried to work it out on his own all week, or, switched to another task, then Bob is responsible for missing his deliverable, and that's inexcusable. It also means that Bob needs to have a chat with you about time management, asking for help, and maybe even finding something that fits his talents better than whatever he was working on last week. This is the kind of thing that will show up on a weekly report and maybe the yearly review if Bob isn't making progress. Rule of thumb: if Bob is making productive steps to get past getting stuck, that's actually a good thing for his yearly review. If he's standing still or going backwards, that's a bad thing.
Let's look at (D), D) Bob didn't work on that assignment, but a different assignment this week. This could go one of two ways: a) Bob was misinformed or had a miscommunication and worked on the wrong project, in which case both you and Bob are culpable for the mistake and missed deliverable (it is your job as his boss to make sure he's on task) or b) Bob knew he was supposed to work on this deliverable and didn't for some reason. Now if Bob communicated to you early about the reason he wasn't working on the deliverable--say it depended on hardware that hasn't been delivered--and you're aware, then no biggy; it's a reason and a good reason (most likely, Bob is not in control of the delivery of hardware). If, however, Bob didn't communicate to you about a solid reason like hardware being missing or worse, Bob preferred to work on another piece of work instead, that's "excuse" territory and doesn't mitigate the lack of work on the promised deliverable.
In the case of him being blocked by missing hardware, which you would typically excuse a behavior for, you wouldn't in this case because he didn't keep you informed. As his boss, you need to know things about promises made, and a deliverable is a promise made; its okay to fail to meet a commitment/complete a promise from time to time, but not okay to surprise your boss with it. As the manager, you take it in the teeth for your team's failures, and you protect them from the rest of the company coming down on them for those failures; if anyone is going to come down on them, it's you, and only with good reason. A good reason is being blindsided by a missing deliverable when you knowing about it sooner could have set expectations appropriately or, in a best case scenario, have you help in removing the blocking issue (ie: getting the hardware faster).
In the case of not working on the project and working on something else instead, something like (C) could have happened or Bob simply chose to abandon an agreed upon plan. In either case, it's bad news--this is an excuse and its not excusable. If you agree to do a piece of work for the team, you need to meet your commitments in order to maintain trust. Failing to do so hurts the team and definitely shows up in yearly review cycles.
Finally, let's look at (E), Bob was late to work every day because of traffic issues, and therefore didn't complete because he didn't have as much time to complete the work as expected. Let's break that down: traffic is something over which you have little to no control. You can control when you leave the house to get to work and whether or not you stop to get an awesome mocha-chino-latte-vanilla-something. But some days, leaving with a lot of time and not doing any extra errands and fate does not smile on you. Suddenly you're sitting in a sea of cars and unable to be at work on time.
In areas where there is only one way to get to work (or maximum, two), this is going to happen occasionally. You can't ask a person to come in an hour and a half early every day in an effort to avoid it. You do talk to the person, or your team, and ask them to let you know it might happen, and have them call you from a cell phone when it does happen so you're not worried about them.
However (and you knew there was a however), doing it every day for a week such that it affects your ability to complete a deliverable on time? That's an excuse, flat out, that doesn't excuse the behavior. If it's temporary road work for the week, day two you leave earlier, leave later (and work later) or work from home. You don't claim you were blindsided by the amount of traffic every day for a week.
The point of the example is to explain that you are responsible for your own actions and so are the folks beneath you. If you can control things that might impact your work, and don't, then, for the most part, it's inexcusable. If you cannot control things that impact your work and don't tell anyone, it's also inexcusable as you are missing out on people being able to help you, and keeping trust with them about what you really can deliver.
At the end of the day, trust amongst the team--including the manager--is what makes things work. It also makes things fun, efficient, productive, and a land of few surprises that you, as a team, cannot handle.