Completely baffled about "set ti isio" vs "os" - Level 2, Challenge 24

I’ve just been trying to do Challenge 24 of Level 2 and I find myself completely mystified as to when an “if” is os and when it’s one of the tas-type things (taset ti, etc).

I thought I had it - the tas stuff all seemed to be about if you/I would do something - e.g. 'sech di’n arafu as “if you would slow down”

But now suddenly there’s also 'set ti isio for “if you want(ed)”. Why? When do you use os and when this tas stuff? I haven’t been able to identify a pattern (other than the “would” pattern, which is now out the window)

I did search the forum topics but what I found was quite technical and didn’t make anything any clearer, at least to me. What is it that determines when you use one and when the other?


You’re not the only one Alan - this is an explanation I gave recently to someone else -

“os” is “if” unless the conditional tense is being used - with the conditional tense, the “if” is kind of hypothetical, and this “if” is petaswn/petaset/petasai etc, which is often shortened to taswn/taset/tasai etc, which in turn is often shortened to 'swn/'set/'sai etc.

Bydda’n mynd os ti’n mynd hefyd - I will go if you are going too
Byswn i’n mynd petaset/taset/'set ti’n mynd hefyd - I would go if you were going too

The confusion can arise because both the conditional byswn/byset/bysai etc and the conditional 'if’s are often shortened to 'swn/'set/'sai etc. So your “would” pattern is not entirely out of the window - it just applies to both the “would” and the corresponding “if”.

Does that help?


Well hears my understanding. Taswn i ( If I (did something)) so that’s conditional on something else happening. So,

Taswn i ennill y loteri, baswn i prynu car newydd
If I won the lottery, I would buy a new car.

Os could be used in a simple sentence like,
Gwisgo y het os dych chi’n oer.
Wear a hat if you’re cold.

I’m not the most advanced Welsh speaker but that’s my understanding. Hope it helps.


That’s what I mean by technical - I have no idea what the conditional tense is.

High school English is woefully inadequate, so most of what I know about the technicalities of language comes from learning Medieval Latin during my Masters. That had all kinds of horrible stuff - subjunctives and ablatives and gerundives - but no conditional tense. I don’t know what that is.


Thank you, and I see what you’re getting at, but isn’t “if you’re cold” also conditional on something else (whether you’re cold or not)?

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Also, my apologies if any of my posts today sound irritable. It’s been a tiring and frustrating day all round.


Conditional tense is when you use would/could/should. It’s used to speculate about what could happen, what might have happened, and what we wish would happen.

So, in my examples above,
Bydda’n mynd os ti’n mynd hefyd - I will go if you are going too
This is a “will happen” scenario, not a “might happen”/“could happen” one.
Byswn i’n mynd petaset/taset/'set ti’n mynd hefyd - I would go if you were going too
This is a “might happen”/“could happen” scenario, not a “will happen” one.

The “if” problem arises because in English there is no difference between a definite “if” and a maybe “if” - we just use “if” for both, so we don’t really take any notice of conditional tense. But in Welsh they are different which takes some getting our heads around because we’re so used to ignoring the difference in English!

Don’t worry Alan - we all get those, especially at the moment!


No because you’re just making a statement.You’re not saying that you have to wear a hat if you’re cold. Wearing a hat is not conditional on being cold.

eg: Taswn i oer. baswn i gwisgo y het. If I’m cold I’ll wear a hat. In other words if something happens then something else will happen.

Wheras, Bydda i gwisgo het os dw i oer . I’ll wear a hat if I’m cold. That’s a choice., saying If I’m cold I’ll consider wearing a hat It’s not conditional.
Does that help or have I made things worse?


The 'Sen option is used when the sentence is talking about something which might happen ie only maybe - depending upon some condition…

Eg. He said he would go if you would… (go too)

… the tricky bit is that the English translation for the conditional part - the second half above - tends to change to make it ‘sound right’ and this can depend on the exact wording that follows - for example…(Changing the above only slightly).

Eg2…he would go if you were going too

Eg3…he would go if you went too

…ie. The English appears to change when the Welsh doesn’t.

So it can be easier to use the fact that the other half of the sentence uses a ‘would’ eg he would go…or, the equivalent apostrophe 'd eg he’d go if…

Rich :slight_smile:

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Ok, I think I’ve got it. Thanks for the help everyone.


Wow! What a brilliant explanation, but admittedly I think that the only reason I can fully understand it is because I’m that far down the ffordd gyda fy Nghymraeg. Having done “Welsh for Adults” for 3 and a bit years now, I had no idea that the full “starting” version of the conditional verb was mewn gwirionedd “petaswn” etc. with the “pe” in front of the taswn… It’s a really difficult balance to know what to teach people from the start, I suppose, in that your brain would explode if from day one they taught you all of what’s contained in your response, but I’m so grateful to be seeing it now. Stuff I learned ages ago with SSIW and not so ages ago with Welsh for Adults now falls into place! Brilliant, diolch yn fawr iawn!

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‘Sech chi’n siarad Cymraeg,’sech chi’n gwybod. I once saw this written down and am I right in thinking it says. Would you be speaking Welsh,you would be knowing( if you spoke Welsh,you would know)or the other way round ‘sech chi’n gwybod ,’sech chi’n siarad Cymraeg …you would be knowing,would you be speaking Welsh(If you spoke Welsh,you would know).

It’s “If you were to speak Welsh, you would know”
The other way around (You would speak Welsh if you were to know) wouldn’t really make sense.

Context is everything when both bits get shortened that much!

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Great explanation Siaron.
Another way of looking at this could be to turn around the English examples above and totally eliminate the word “if” from conditional sentences:
"Were you to go, I would go too": Welsh uses “taswn” and its variations.
"If you go, I will go too": Welsh uses “os”.
Is this correct?
Were I to have made a mistake here, would anyone correct me?
If I’m correct, will someone tell me?

Spot on, Baruch! Taking out the ‘if’ in conditional tense certainly does help - but it’s such a hard habit to break!

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I’m not suggesting that we do take out the “if” in conditional sentences - but it helps to show that the word “if” in English actually has these two usages that we never think about or realise, until we come across another language that uses different words for each usage. (Same in Hebrew, by the way: two different words, so I’m used to the difference.)


The grammar books explain the difference in terms of open and closed conditions. An open condition suggests the “if” might still happen. If you go, I’ll go…if it’s cold I’ll wear a hat. The point is you might go and it might be cold. The possibility is open – use os and the present or future tense.
But if you say if it were cold I would wear a hat, that suggests it isn’t cold and you are referring to a possibility that hasn’t occured. Similarly: if you were going I would go, suggests that I don’t think you are going and once again I am referring to a counterfatual possibility. That is a closed if condition and needs the pe form of if: petaset ti etc.
The Welsh have terrible habit of eliding syllables and shortening words so the structure of the sentence becomes impenetrable. The only language I know that is nearly as bad is Portuguese. People who can read Portuguese fluently can’t understand anything when it is spoken. I’m a bit like that in Welsh.


My limited knowledge of Manx, shows me that it also likes to shorten stuff. I can recognise some words as being a shortened and adjoined version of two words from Irish or Scottish. :slight_smile:

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Thank you for the initial question, because that’s exactly what’s just baffled me with L2 Challenge 24! And thanks for all of the replies and explanations. You’re all awesome!